mtn *****ing from me

i have cancelled my data contract with mtn on the 7th March 2021, i was helped by Thelma Ngobeni to do the cancelling, she advise me that instead of cancelling why dont i move the contract to my mtn 0 which means i will get 2gigs per month and pay nothing for it, i agree to that not knowing i am putting myself in unsolvable situation, at the end of the month i was debited with R100, as she said i should email her i did so but there was no respond on her side, i called and was told it was due to the fact that by the time of cancellation there was R100 which was already billed to my account, the following month R468, was debited to my account, i called mtn, sent an email to retention, customer services and Thelma still no response and i kept on calling them until the supervisor by the name of Msizi assisted me and he told me that he will request that a credit should be passed on my account as mtn is still billing me on month to month for the services i dont receive, today the 01 june 2020 i wake up to mtn has debited my account with R1562, have sent an email to him still waiting for the response, can someone please assist with this, i will be reversing the debit order and dont expect to be sent to credit bureau for this nonsense, its been 3months since the problem started