diff --git a/TheMiddleman/BusinessLogic/MiddlemanService.cs b/TheMiddleman/BusinessLogic/MiddlemanService.cs
index 112ca46..15f859a 100644
--- a/TheMiddleman/BusinessLogic/MiddlemanService.cs
+++ b/TheMiddleman/BusinessLogic/MiddlemanService.cs
@@ -44,7 +44,7 @@ public void Purchase(Middleman middleman, Product selectedProduct, int quantity,
         }
     }
 
-    public void Sale(Middleman middleman, Product product, int quantity)
+    public void SellProduct(Middleman middleman, Product product, int quantity)
     {
         middleman.Warehouse[product] -= quantity;
         if (middleman.Warehouse[product] == 0)
@@ -54,20 +54,14 @@ public void Sale(Middleman middleman, Product product, int quantity)
         middleman.AccountBalance += quantity * product.SellingPrice;
     }
 
-    public void IncreaseWarehouseCapacity(Middleman middleman)
+    public void IncreaseWarehouseCapacity(Middleman middleman, int increaseAmount)
     {
-        int increaseAmount;
-        if (!int.TryParse(ConsoleUI.GetUserInput(), out increaseAmount) || increaseAmount <= 0)
-        {
-            ConsoleUI.ShowErrorLog("Vergrößerung des Lagers abgebrochen.");
-            return;
-        }
         int costForIncrease = increaseAmount * 50;
         if (middleman.AccountBalance < costForIncrease)
         {
-            ConsoleUI.ShowErrorLog($"Nicht genug Geld für die Vergrößerung des Lagers vorhanden.\nVerfügbares Guthaben: ${middleman.AccountBalance}");
-            return;
+            throw new InsufficientFundsException($"Not enough funds for warehouse expansion. Available funds: ${middleman.AccountBalance}");
         }
+
         middleman.AccountBalance -= costForIncrease;
         middleman.MaxStorageCapacity += increaseAmount;
     }
diff --git a/TheMiddleman/DataAccess/IMiddlemanRespository.cs b/TheMiddleman/DataAccess/IMiddlemanRepository.cs
similarity index 88%
rename from TheMiddleman/DataAccess/IMiddlemanRespository.cs
rename to TheMiddleman/DataAccess/IMiddlemanRepository.cs
index 1794f01..3f93983 100644
--- a/TheMiddleman/DataAccess/IMiddlemanRespository.cs
+++ b/TheMiddleman/DataAccess/IMiddlemanRepository.cs
@@ -2,7 +2,7 @@
 
 namespace TheMiddleman.DataAccess
 {
-    public interface IMiddlemanRespository
+    public interface IMiddlemanRepository
     {
         List<Middleman> RetrieveAllMiddlemen();
         List<Middleman> RetrieveBankruptMiddlemen();
diff --git a/TheMiddleman/DataAccess/MiddlemanRespository.cs b/TheMiddleman/DataAccess/MiddlemanRepository.cs
similarity index 92%
rename from TheMiddleman/DataAccess/MiddlemanRespository.cs
rename to TheMiddleman/DataAccess/MiddlemanRepository.cs
index f72ff70..8083a31 100644
--- a/TheMiddleman/DataAccess/MiddlemanRespository.cs
+++ b/TheMiddleman/DataAccess/MiddlemanRepository.cs
@@ -2,7 +2,7 @@
 
 namespace TheMiddleman.DataAccess
 {
-    public class MiddlemanRespository : IMiddlemanRespository
+    public class MiddlemanRepository : IMiddlemanRepository
     {
         private List<Middleman> _middlemen = new List<Middleman>();
         private List<Middleman> _bankruptMiddlemen = new List<Middleman>();
diff --git a/TheMiddleman/UserInterface/ConsoleUI.cs b/TheMiddleman/UserInterface/ConsoleUI.cs
index c42aae4..3d2ba8d 100644
--- a/TheMiddleman/UserInterface/ConsoleUI.cs
+++ b/TheMiddleman/UserInterface/ConsoleUI.cs
@@ -255,7 +255,20 @@ private void ShowSelling(Middleman middleman)
 
     private void ShowWarehouseExpansion(Middleman middleman)
     {
-        ShowExtendingWarehouse(middleman);
+        try
+        {
+            ShowMessage("How many units do you want to expand the warehouse by? ($50 per unit)");
+            int increaseAmount = int.Parse(GetUserInput());
+            _marketService.MiddlemanService().IncreaseWarehouseCapacity(middleman, increaseAmount);
+        }
+        catch (InsufficientFundsException ex)
+        {
+            ShowErrorLog(ex.Message);
+        }
+        catch (FormatException)
+        {
+            ShowErrorLog("Invalid input. Please enter a positive number.");
+        }
     }
 
     private void NotifyInvalidMenuChoice()
@@ -263,12 +276,6 @@ private void NotifyInvalidMenuChoice()
         ShowErrorLog("Ungültige Auswahl. Bitte erneut versuchen.");
     }
 
-    private void ShowExtendingWarehouse(Middleman middleman)
-    {
-        ShowMessage("Um wie viel Einheiten möchten Sie das Lager vergrößern? ($50 pro Einheit)");
-        _marketService.MiddlemanService().IncreaseWarehouseCapacity(middleman);
-    }
-
     private void ShowAllProducts()
     {
         List<Product> products = _marketService.ProductService().GetAllProducts();