paying and being billed

i am being being billed since august last year for a contract that i had cancelled. the contract should have been effective withing 14days, had i been satisfied. i did cancel withing the time frame of 14 days. interactive technologies is a sub contracted company to vodacom. they did collect the phone that the contract had issued, but did not cancel my contract as agreed. i visited vodacom's vodashop for plea to help. the attendant gave me info of the company responsible only and asked me to call them directly. the phone number of Interactive technologies do not even exist! ***. please help.