Telkom and it's bad service

I am so disappointed by the service I'm receiving. I canceled my contract on the 1st of July which is supposed to end with the debit for 1st August. Today I received an invoice which says I must pay for end August again and when I call the contact center the story has now changed and the sms I received is now being regarded. I spent almost an hour with a call center agent trying to convince me the sms and call I received from telkom are wrong.