Poor service

Hi My name is Freddie and I'm really not happy with the service I'm getting from Telkom (Mondo) I've signed up for a contract with them where by R139 p/m will be deducted. It was so for about three months then it started going to about R700 to R1000......... I made an arrangement to pay it off and cancel the account, I've paid it off on the 26th April but now they telling me that the money doesn't reflect on their system, I've spoken to four consultant already and they all telling the same story everyday with no results......I feel like I'm being taken for a ride. Telkom please attend to this urgently as now I'm on credit review.....