Cell C Worst Service - ( As usual)

I am highly annoyed at the service of this business. ( as usual) I had canceled my old cell a phone contract a MONTH before and i am STILL being billed for this! When I call in, I get told that no one had recorded my request on their system and that they will put the request in to be cancelled and this will take a month to kick in but i will STILL need to pay in the last month! I was then told that I need to call in again 2 days later to make sure my request was submitted. WHY must I follow up on THEIR jobs?? THEY are PAID to work and PAID to make sure requests are for-filled by the clients. CELL C admin is a joke and needs to train their staff accordingly.