I want my contract cancelled ASAP!!!

Took a wifi router with Kabelo who from the onset was just not honest about anything! I asked for a top up option and he put me on the opposite, their servicing department tried to assist advising me to go to the store, Kabelo did admit he made a mistake(have the recording for that phone call) we came to an agreement that he will pay all the amount they billed me n that I'd pay my normal sub fee R250, he said he will make an arangement for them to only debit R250 on the 25/08/15 that n he'll pay 800 then the rest he would pay the following month, I got debited 1,8 and when I called Kabelo he now comes up with some more lies that he didn't say anything like that, I'm tired of being taken from pillar to post with no resolution, and I'm very unsatisfied, he was just pushing sales!!! He said he's made an arrangement with their accounts department to only take R250 as he will pay the rest, but no, I got debuted 1,8 n now the bank has charged me for an unpaid debit, cell c must pay for that, that's what you get for employing people that are not honest!!! I want them to cancel the contract ASAP, I can't anymore I've heard it with Kabelo he disgust me!!!