Clicks service pathetic

Clicks at Bela Bela Mall is the worst!

I made a purchased (diapers for my baby). We paid and then they couldn't print a slip. They told us the transaction didn't go through (even though on my banking app and email I proof that it did). They said I must pay again or give back the purchase, I can collect it when they said it is through. How can I leave diapers - it is a necessity. So the package is with them now eventhough I did pay for it.