Never use mtn for contract

I got a contract phone for my mom which expired 2 years ago. The contract was on month to month and I did cancel ast year but that was not done. I continued paying the R160 with no benefits till they charged in April and May an average fee of R500 for each month. When I enquired they said it's unlimited bundles and airtime. This was not even part of the contract for it to be active. My mother always topped up airtime and data when ranout. There was never a time she experienced unlimited. I canceled again last week and asked if there's no outstanding balanced. The consulted said the cancelation will only be active a month later and cannot be immediately l. Yesterday my mom received an sms to pay an outstanding R433 or account will be suspended. When I queried the consultant said the contract was not canceled. The outstanding amount is for may that time she didn't use the phone cause it was suspended for the April and May outstanding fee. I paid for services that were not used and didn't subscribed for. This is a reap off from someone who has been paying for not getting benefits i would have upgraded but decided not to and port to another network provider.