FNB charged my account twice for a single purchase

I want to start of by saying FNB has the worst call centre. I purchased something online, however a few minutes after the purchase I read the fine print again and realised I actually didn’t want the product so I messaged FNB on the secure chat to please cancel the transaction, this was literally 5 mins after the purchase was done on my credit card, the consultant said the reversal can’t be done and I need to fill in a dispute form and wait 10-14 days to have this done purchase cancelled or I can contact the place I made the purchase and ask them to cancel so I said fine. I emailed the store and asked for the purchase to be cancelled, 3 days later I got an email from the store with the credit of my purchase as proof it was done. FNB credited on straight facility with the about but then charged that whole amount to my budget facility. When I checked my account and found this error I immediately called their call centre to speak to an agent. I was transferred to five different agents, remember I had to explain the problem five times only to be told at the end that I need to fill in a dispute form and someone will contact me. I filled in the dispute form and sent it through on 2 September. Still NO ONE has contacted me.