MTN month to month contract

i struggling to cancel a month to month internet package with MTN. i first went to visit the actual stores for the contract to be cancelled and the shop assistance refused to help. i wrote to customer service on the 07/02 with the below senior managers to assist and they collect the device but i am still getting notifications to pay for the service that i am not using. MTN SA wants money for service that is not rendered. if they can explain why i should pay for a router that has been handed over to them. i was struggling with connectivity and they failed to address the issue hence i cancelled the contract.

Lindi Kekana Kashan Sinmurathi Renier Voges Dheveshan Pillay