4 months to sort out billing and still no help

It has been 4 month now that I keep calling MTN for the billing error, I have made of 10 calls to sort it out. In September my monthly payment was 752.89, I even have sms proof of this , come mid October I received about 15 sms and emails with a different pricing of 780 something , I called and they advised that itemized billing was added I told to remove it as I never check emails and if my data depletes i will just top up As usual why was it added later? so it’s a useless add on can they please remove it and the agent advised that they had , I pay my normal amount and it then turn out they added to my other contract instead of removing it , come November I call again for the same issue and the one agent managed to remove on the one number but not the second one as I have 2 contracts with mtn. in December my lines get suspended due to the outstanding amount of the itemized billing which I long asked to remove from the first day I realized it was added to my bill. This is my work line I cannot be unreachable. Early December I call again the new agent advised that I make a payment arrangement in order for my lines to be opened as collections department are the only one that can sort it. I need my lines active so I agreed . I called a few times more in December to sort it out and reach collections who I am never transferred to . The last agent I explain the situation all over again for like the 10th time. Are thé these calls not recorded??? Are the no notes left in the system to aid the next agent on the matter at hand ?? The last agent then says it’s a simple matter that the itemized amount should be credited to my account because of the error and that I needed to just pay my normal amount of 752.89 . On thé 31st of December I make payments and then I receive smses that my lines are suspended yet again !!! Due to the itemized outstanding amount ! It has been 4 months of the same story back and forth ! It really exhausting and really really horrible service for one small thing that should have been dealt with easily and even today I tried calling mtn explaining the whole story yet again the collections team are never reachable and when I go to the MTN store to rectify this nobody can assist! It is beyond upsetting.