diff --git a/src/Managing.Application.Abstractions/Services/IKaigenService.cs b/src/Managing.Application.Abstractions/Services/IKaigenService.cs
index 07ce632..d8611f4 100644
--- a/src/Managing.Application.Abstractions/Services/IKaigenService.cs
+++ b/src/Managing.Application.Abstractions/Services/IKaigenService.cs
@@ -1,3 +1,5 @@
+using Managing.Domain.Users;
+
 namespace Managing.Application.Abstractions.Services;
 
 public interface IKaigenService
@@ -5,16 +7,16 @@ public interface IKaigenService
     /// <summary>
     /// Debits user credits for a backtest operation
     /// </summary>
-    /// <param name="userName">The username to debit</param>
+    /// <param name="user">The user to debit</param>
     /// <param name="debitAmount">The amount to debit</param>
     /// <returns>The request ID for tracking</returns>
-    Task<string> DebitUserCreditsAsync(string userName, decimal debitAmount);
+    Task<string> DebitUserCreditsAsync(User user, decimal debitAmount);
 
     /// <summary>
     /// Refunds user credits if debit operation fails
     /// </summary>
     /// <param name="requestId">The original request ID from debit operation</param>
-    /// <param name="userName">The username to refund</param>
+    /// <param name="user">The user to refund</param>
     /// <returns>True if refund was successful</returns>
-    Task<bool> RefundUserCreditsAsync(string requestId, string userName);
+    Task<bool> RefundUserCreditsAsync(string requestId, User user);
 }
\ No newline at end of file
diff --git a/src/Managing.Application/Backtesting/Backtester.cs b/src/Managing.Application/Backtesting/Backtester.cs
index 2a76e4d..9197bf4 100644
--- a/src/Managing.Application/Backtesting/Backtester.cs
+++ b/src/Managing.Application/Backtesting/Backtester.cs
@@ -92,7 +92,7 @@ namespace Managing.Application.Backtesting
             {
                 try
                 {
-                    creditRequestId = await _kaigenService.DebitUserCreditsAsync(user.Name, 3);
+                    creditRequestId = await _kaigenService.DebitUserCreditsAsync(user, 3);
                     _logger.LogInformation("Successfully debited credits for user {UserName} with request ID {RequestId}", 
                         user.Name, creditRequestId);
                 }
@@ -127,7 +127,7 @@ namespace Managing.Application.Backtesting
                 {
                     try
                     {
-                        var refundSuccess = await _kaigenService.RefundUserCreditsAsync(creditRequestId, user.Name);
+                        var refundSuccess = await _kaigenService.RefundUserCreditsAsync(creditRequestId, user);
                         if (refundSuccess)
                         {
                             _logger.LogInformation("Successfully refunded credits for user {UserName} after backtest failure", user.Name);
diff --git a/src/Managing.Infrastructure.Web3/Services/KaigenService.cs b/src/Managing.Infrastructure.Web3/Services/KaigenService.cs
index 9a53a49..73dcd14 100644
--- a/src/Managing.Infrastructure.Web3/Services/KaigenService.cs
+++ b/src/Managing.Infrastructure.Web3/Services/KaigenService.cs
@@ -1,6 +1,7 @@
 using System.Net.Http.Json;
 using System.Text.Json;
 using Managing.Application.Abstractions.Services;
+using Managing.Domain.Users;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Nethereum.Signer;
@@ -56,22 +57,15 @@ public class KaigenService : IKaigenService
         }
     }
 
-    public async Task<string> DebitUserCreditsAsync(string userName, decimal debitAmount)
+    public async Task<string> DebitUserCreditsAsync(User user, decimal debitAmount)
     {
         try
         {
+            var walletAddress = GetUserWalletAddress(user);
             var requestId = Guid.NewGuid().ToString();
             
-            // Create the payload for signing
-            var payload = new
-            {
-                RequestId = requestId,
-                UserName = userName,
-                DebitAmount = debitAmount
-            };
-
             // Create the message to sign (concatenate the values)
-            var message = $"{requestId}{userName}{debitAmount}";
+            var message = $"{requestId}{walletAddress}{debitAmount}";
             
             // Sign the message
             var signature = SignMessage(message, _settings.PrivateKey);
@@ -80,13 +74,13 @@ public class KaigenService : IKaigenService
             var requestPayload = new
             {
                 requestId = requestId,
-                userName = userName,
+                walletAddress = walletAddress,
                 debitAmount = debitAmount,
                 signature = signature
             };
 
-            _logger.LogInformation("Debiting {Amount} credits for user {UserName} with request ID {RequestId}", 
-                debitAmount, userName, requestId);
+            _logger.LogInformation("Debiting {Amount} credits for user {UserName} (wallet: {WalletAddress}) with request ID {RequestId}", 
+                debitAmount, user.Name, walletAddress, requestId);
 
             var response = await _httpClient.PutAsJsonAsync(
                 $"{_settings.BaseUrl}{_settings.DebitEndpoint}", 
@@ -102,24 +96,26 @@ public class KaigenService : IKaigenService
             }
 
             var result = await response.Content.ReadFromJsonAsync<KaigenResponse>(_jsonOptions);
-            _logger.LogInformation("Successfully debited {Amount} credits for user {UserName}", 
-                debitAmount, userName);
+            _logger.LogInformation("Successfully debited {Amount} credits for user {UserName} (wallet: {WalletAddress})", 
+                debitAmount, user.Name, walletAddress);
 
             return requestId;
         }
         catch (Exception ex)
         {
-            _logger.LogError(ex, "Error debiting credits for user {UserName}", userName);
+            _logger.LogError(ex, "Error debiting credits for user {UserName}", user.Name);
             throw;
         }
     }
 
-    public async Task<bool> RefundUserCreditsAsync(string requestId, string userName)
+    public async Task<bool> RefundUserCreditsAsync(string requestId, User user)
     {
         try
         {
+            var walletAddress = GetUserWalletAddress(user);
+            
             // Create the message to sign (concatenate the values)
-            var message = $"{requestId}{userName}";
+            var message = $"{requestId}{walletAddress}";
             
             // Sign the message
             var signature = SignMessage(message, _settings.PrivateKey);
@@ -128,12 +124,12 @@ public class KaigenService : IKaigenService
             var requestPayload = new
             {
                 requestId = requestId,
-                userName = userName,
+                walletAddress = walletAddress,
                 signature = signature
             };
 
-            _logger.LogInformation("Refunding credits for user {UserName} with request ID {RequestId}", 
-                userName, requestId);
+            _logger.LogInformation("Refunding credits for user {UserName} (wallet: {WalletAddress}) with request ID {RequestId}", 
+                user.Name, walletAddress, requestId);
 
             var response = await _httpClient.PutAsJsonAsync(
                 $"{_settings.BaseUrl}{_settings.RefundEndpoint}", 
@@ -148,16 +144,34 @@ public class KaigenService : IKaigenService
                 return false;
             }
 
-            _logger.LogInformation("Successfully refunded credits for user {UserName}", userName);
+            _logger.LogInformation("Successfully refunded credits for user {UserName} (wallet: {WalletAddress})", user.Name, walletAddress);
             return true;
         }
         catch (Exception ex)
         {
-            _logger.LogError(ex, "Error refunding credits for user {UserName}", userName);
+            _logger.LogError(ex, "Error refunding credits for user {UserName}", user.Name);
             return false;
         }
     }
 
+    private string GetUserWalletAddress(User user)
+    {
+        if (user?.Accounts == null || !user.Accounts.Any())
+        {
+            throw new InvalidOperationException($"No accounts found for user {user?.Name}");
+        }
+
+        // Use the first account's key as the wallet address
+        var walletAddress = user.Accounts[0].Key;
+        
+        if (string.IsNullOrEmpty(walletAddress))
+        {
+            throw new InvalidOperationException($"No wallet address found for user {user.Name}");
+        }
+
+        return walletAddress;
+    }
+
     private string SignMessage(string message, string privateKey)
     {
         var signer = new EthereumMessageSigner();