Disaster at point of payment

Bought items at Cape Union Mart Vaalmall today, swiped my credit card and was told the transaction did not go through. At the same time received a sms from fnb stating purchase was reserved, therfore I refused to swipe again. Assistant manager explained that although the transaction went through on my side it was not completed on their side and it will be reversed. I had the option to swipe again and take their word for reversing the first transaction but had no indication of when. This would amount to nearly R6000 and I was not inclined. They were unable to reverse the transaction and refused me leaving with the items saying the reversal will take place. After about an hour of waiting and no conclusion I left with nothing but a letter of promise to reverse my transaction. Clearly there is a problem with the card machine payment system at this store, because it happens frequently according to the assistant ! No shoes + no jacket + still no reversal = no customer