Doubled Charged & No Refund as Yet

I visited Grand Slam on the 15th of November for a Sunday lunch with some mates. At the end of the meal I paid and the waiter told me the transaction had not gone through so I swiped again. I discovered a day or two later on the internet banking that they had charged me twice. Initially I tried to phone but had no luck. I sent an email and received my first response from Johan on November 24th. We have since traded various emails each back and forth, he is always courteous on the mails but his promises have gone no where. He promised last week Friday saying \I will refund you the money from my personal account and get the money bank from the bank"";I will never support them again."""