Wimpy Villiers double charging

On the first of February on my way back from a home visit, I had a very unpleasant experience at the Wimpy in Villiers. The waiter Teboho was adamant that we should use the on table ordering system and pay there instead of at the counter. With my first payment the machine indicated that my payment failed and the waiter said I should try again. The payment unfortunately went through twice. The waiter assured me that it would be reversed but to this day this has not happened. The waiter gave me his number to call if it did not reverse. After a week I called and was assured that it will be sorted out. After a lot of follow up calls from my side I still do not have my money back. This is a very frustrating experience for something mundane that could have been sorted out on the day. I hope that Wimpy will respond and set this right.