Contract Cancellation

I lives in Gauteng and my daughter in Western Cape. I had an MTN contact for years, but I have cancelled mine, because of the poor service and let another provider take over my number. I kept my daughter's Top up contract at MTN, she told me in April that she are going to change to another service provider. My normal monthly payment for that account was R169.00. In May/June MTN phoned me and asked me what is happening with this contact. I told them that this contract must be cancelled. I received an account for R19.00 at that stage and I presumed that this will be the last payment. From then on I started receiving MTN accounts for R169.00 again. What is the matter with tese people. Service, accounts, everything is terrible. I phoned MTN and told them a few times that I am not paying the outstanding balance, but the account is piling up. They must go back and listen to the recordings, if it is recorded