Complain for contract cancellation ***

I'm not happy with MTN's customer service. On July 8, 2022 (reference number- ***), I contacted customer service. My contract was not cancelled despite my efforts. My contract was for 24 months and expired on August 11, 2022. I gave MTN a one-month cancellation notices on the 8 July 2022. On the 12th of August, 2022. I tried calling the customer services all day but couldn't get through to anyone who could tell me if my contract had been cancelled. I received an SMS on the evening of August 12, 2022 "your contract is changing from R346.96 to R 540.483 on a month-to-month term." Which I did not subscribe to and am now being charged even more. I followed up with MTN three times using this email address: ***, ***, and ***. I didn't get any help.