contract not cancelled

I cancelled my contract on the 21st of April and i was given a reference no *** and was told my contract will be cancelled within 2-7days even today its not done. They billed me a Thousand plus in May and i dnt know how much will be billed in June. I want my money back and the contract to be cancelled immediately nothing should billed cause they breached the contract.Their call centre is incompetant they have inconvinienced me and i dnt who to call. I even went to Mtn in Newtown mall they cant help just because of strike. I ported my number to Mtn believing for the best only to drown myself into debt.