MTN Worst Customer Service!!! Real Ripp Off

MTN Ref *** & *** & 1- *** I had a con2 year contract with MTN for an LTE line, the contract term ended in December2022, MTN sent me a sms indicating that when the contract comes to an end my premium will change from R299 to R699 on the 5th December I sent an email to MTN at 14:45 to inform them that they should not increase my premium and that they should cancel the contract with immediate effect. They did not do so and deducted R699 for the month of December2022 and R699 for the month of January2023, I returned the payment. Surely it cannot be legal that MTN can just change a contract and increase the contract amount without permission if i contract period expires, should they not get my permission? They should have called me to confirm if I wanted to continue. with this and if i wanted to cancel..... I have phoned so many agents in MTN and all I am getting is the runaround no one has assisted me.