This shop doesn't tell you that they're charging you 50p more if you pay by card, they just tell you the original price you're supposed to pay, key in 50p more on the contactless machine, then cover the machine in a very tricky way to prevent you from checking how much you're paying and once you've paid they immediately take away the machine and throw away your receipt. (I only realised they charged me more by the time I got home by looking at my googlepay app)
There was also once they charged me 60p more even when I paid by cash. read more