PLEASE return my money

Today I bought me ONE strawberry slushy and ONE pepper steak pie, totals r28:00 and because I never had issues before with payment I tapped, following the payment I saw the guy who assisted entered r42, he then told that the payment won’t go through because he cancelled it. He then proceeded with putting the correct amount on the machine which was r28 I then made a payment again. As I was leaving the mall, and I entered the taxi I saw that both r28 and r42 was deducted. At this time it was too late for me to turn back. I’m just very very upset about this. Another thing I want to add, when I asked the salesman why he made it 42rand he said he wanted to combine the slip of me and my friend who also purchased something and made a full payment for her meal but he still proceeded to add her things on my slip. I feel ******! Salesman name is MERCY . My order number was 353. And the invoice number is 26855.