Checkers make you pay double

I went to Checkers at the Glen Shopping centre to buy a few things. When I went to pay I had a lovely cashier who helped me. After I had made payment which showed approved on their machine and through my bank I was asked to wait for my slip as there was a problem with their printer. Their front line manager was called as it wasn't working. And she needed to reboot the till. This didn't work and I was told I need to pay again. I then asked to speak to the store manager who said to me I had to pay again as they couldn't print my slip. Really what do they do if a person doesn't have the funds to pay again? It was really shocking service from this store and they have none nothing no customer service. Really disappointed in checkers and I am considering going to social media with regards to this!!!!