Bring back my money

In March 2020 MTN convinced me not to cancel my contract with a lucrative deal, indeed I fell for it, guess what, they continued taking money from my account for months but I was not getting what they promised... after a long fight with them they eventually agreed that they were at fault. I asked for a refund and my contract to be canceled and my number be converted to pre-paid so I can port to another network. My contract was cancelled on a Friday, from that day I kept on calling them and they were telling me the conversion takes 2-24 hours, guess what, I was only able to use my phone on the Tuesday... it took more that 90 hours for my number to be finally on prepaid and I could use my phone. We wont on fighting about my refund, in the 9 September 2020 I received an sms from MTN saying my refund has been processed to my bank, it the 4th October 2020 today and I'm yet to see it reflect in my account. I asked them for a proof of payment and still they cant produce that...