Dissatisfied customer regarding refund

I had ordered a meal from KFC on the 2 December 2023. There was an issue with the app on that day as the ordered was returned to the store, however the funds was deducted off my account of an amount of R410.60. I then called KFC customer care department and was informed that I would be refunded in 7-14 days. I then re ordered about 10 minutes late and received my order. I waited the 14 days and called around the 21 December and was informed that I it was working days and that I needed to wait another 2 days which was not a problem. However today on the 12 January 2024, I still have not received my refund and when I called I was informed the refund was done on the 2 December 2023 and they emailed me the statement. I then called the bank and they had informed me that the refund was not done and they informed me that I need to get an authorization letter to release the funds. Firstly I had spent money on phones calls because KFC customer care number is not toll free. Secondly KFC should have known to give me a letter to authorize the release of the funds. It's over a month and it's back and forth. They delay on their responses with regards to emails. I have never had an issue with their service before but this refund issue is frustrating me