Lack of communication !!!!!!!

Dear Telkom

I took a contract for a laptop 2 years ago and my contract ended this year may 2017 and i went to fill in cancellation forms at Southgate mall in June as i did not want to continue with the contract, but every month im being billed not sure for what? and now the amount has reached R 636.38 that i need to pay. I called last month to the billing the department and one of your agents said the last amount that had to be paid before canceling has not gone through which i was not inform about in the store as i would have paid at that moment. In my knowledgement the cancellation has gone through 5 months and no communication of my cancellation progress or delays but im being billed for something i do not want anymore. PLEASE STOP BILLING ME I DO NOT WANT TO CONTINUE WITH THE SERVICE!!!!!!!!!!