Bad service

I bough streetwise mix at KFC Karaglen on the 10th February and gave my card to the till operator. She gave me the machine to put a pin and I gave it back to her. In 2 to 3 minutes she said the machine doesn't have network. She then took another machine and swiped my card and gave it to me to put a pin, of which I did and the transaction was successful. When I got to the office I checked my phone and found that the first transaction also went through so I paid twice for 1 streetwise mix. I phoned them and the supervisor gave me an email address and told me to email my statement since I couldn't go back as it is far from my work place. I sent a follow up email on the 14th February, I didn't get any response. To date I haven't heard anything from them. I love KFC and I'm so disappointed by their service and wonder how many people experienced the same thing and reported it without success.