Bad experience and service.

PEP Florida Roodeport. I bought a few items in store including a sport bottle and I was charged twice. I am pretty sure this was a genuine mistake from the cashier. I checked my slip like always before I left the store and for a refund. I was then asked if I can take anything equivalent to the amount, said no,I didn't need anything else. I was told if I do a refund I won't get my slip back. I then asked if at least they can make a copy and give me a copy. I was told they don't do that . It was a back and forth argument and the manager was not helpful at all . She kept on saying to the cashier so what are you going to do about the receipt. The cashier kept on saying Chomi I will need the receipt. I told her I will need it too and I don't need to explain to you why ? She ended up giving me my receipt after a long argument which made me feel uncomfortable.