Upgrading of numbers done internally by MTN without customers consent.

In 2021 the 2 month contract came to an end it was placed on month to month. I requested twice via 135 to MTN to cancel the number/line. They say they captured it but does not cancel it. months later I must still pay for this line. Jan 2022 I get SMS that the line has been upgraded and they continue as per normal. I phoned them they say they cannot help i must phone MTN Mobile Plus as they did the upgrade. MMP says it take 7 days to investigate and check voice records. a week later no response. So is this the norm that MTN and MTN Plus just upgrades lines themselves and customers must pay for it? I am gatvol of this S*&^$. Today a agent tells me from MMP they dont have managers contact details to assist me they will log it and then wait for feedback. No manager available due to covid protocol that was her story.... Greg