I am still billed after cancellation

I cancelled my contract and changed service providers but kept my number on the 30th of May. MTN excepted this, according to customer support my account is inactive but I've been receiving invoices and the contract amount has been deducted from my account. Because my account is inactive I need to contact the call center but the call center doesn't respond.<br> According to Customer Care I have to talk to the call center and even the branch can't help me or get hold of the call center.<br> I received an invoice again this month and it will be deducted again the end of this month. This is not exceptable.<br> Regards<br> Michelle