private void btnNext_Click(object sender, EventArgs e) { HelperStaticClass.guests = GetGuestsFromForm(); bool tempBool = true; foreach (Guest guest in HelperStaticClass.guests) { bool result = guestController.GuestControll(guest); if (!result) { MessageBox.Show("Error while adding guests!"); tempBool = false; HelperStaticClass.guests.Clear(); HelperStaticClass.guestsDictionery.Clear(); break; } } if (tempBool) { decimal price = ReservationPriceCalculator(HelperStaticClass.reservationStatic); HelperStaticClass.reservationStatic.TotalPrice = price; FinalReservationScreenOpen(); } }