Debiting the wrong amount monthly

I upgraded my contract I received a message stating that the billing was incorrect and it will be correct this was in November last year We are in February and still this has not being fixed I was charged almost R798.99 for an account bill of R299 -01/12/20 Month of January I am charged a further R518.27 and now again i am charged R299 1st February I have been up and down to MTN 6 times in total each time someone trying to log a complaint or assist with feedback and to date MTN is still sitting with a lot of my money and there is no way to get my money back Message received on the 20.11 that the bill is not correct Ticket numbers:*** *** The contract is on the number *** my cellphone number is on the records I would appreciate this matter looked into