MTN Overcharges on Debit Order and disappoints YET AGAIN!

I am highly disappointed and disgusted with MTN. I ordered their Online Exclusive Black Friday Deal where you get 100GB of data for R299 per month. I received the package from the courier 07/12/2020 and struggled to get the SIM Card Activated. Could not get hold of anyone on their call assist line, managed to get hold of someone on their Facebook Messenger, was given a contact number to call "free from an MTN Number", which I do no have since it is a Wifi SIM Card I received, was bounced around to several people and kept on hold for 30 min before I eventually hung up. The correspondence on messenger went quiet for a week and eventually Nosipho from MTN responded after I posted about it on social media. I finally had my SIM Card activated on 18/12/2020. I asked Nosipho if my account would be adjusted to bill me pro rata since more than half the month had gone by where I had no connectivity and I was reassured that it would. Well, it was not! In fact, I was debited R491.90! How on earth does that work?? A deal for R299 per month is almost doubled for less than half a month (13 days) of connectivity!? I was previously a contract holder with MTN for almost 10 years and changed service providers because of an incident just like this. This has only been the first month of my new contract with them again and already I am having problems. I want answers, I want my December account adjusted to pro rata as I was promised and I want the money owed to me to be refunded in full!! If not, then I want the contract terminated. I am not sitting with this kind of nonsense for 24 months.