Always something missing from order

I went through the drive through today and ordered milkshakes and caramel iced coffee. It was very busy and chaos with the loadshedding. When I arrived home, one of the milkshakes weren't given to me and the caramel iced coffee had no caramel in it, it didn't even have any sugar in it and tasted horrible! I've been trying for 2 hours to phone them, but they don't answer the phones. This is a regular occurrence with them that there is always something missing from the order!