Cancellation of Data contract

I have a Data contract with MTN that ended on the 27th July 2022. I went to the Pretoria Church Street branch to cancel it as I got an SMS that my contact will go on a month to month basis from the amount of R179 to R579 imagine!!!!! I’m the branch I was told to call 135 and select option 3 for retentions. I call every day and hold for an hour+ being put on hold only for my call to be cut off without getting any assistance. What a joke! I’ve sent numerous emails to retentions@Mtn with only automated response’s getting back to me.