public static Customer HaveYouBeenHereBefore() { var currentCustomer = new UserSystem(); Console.Write("Welcome! Have you been here before? (y/n):"); string mainUserInput = Console.ReadLine(); try { switch (mainUserInput) { case "y": return(currentCustomer.OldCustomer()); case "n": return(currentCustomer.AddCustomer()); default: Console.WriteLine("Not a valid option. Try again"); return(HaveYouBeenHereBefore()); } } catch (FormatException) { Console.WriteLine("You have to enter (y/n) Try again"); return(HaveYouBeenHereBefore()); } }