//To complete an order, table needs to be set free and payment needs to be completed. Two methods are combined, thats why they're together in here
 public void CompleteOrder(Order order)
 {
     try
     {
         order_db.CompleteOrder(order);
     }
     catch (Exception e)
     {
         throw new Exception("Chapeau application couldn't connect to the database. Therefore we can't register your payment.");
     }
 }