Numerous charges for expired services

December last year I cancelled two 3G contracts and two BIS services with Vodacom. After numerous contacts and numerous assurances I still got billed every month until finally in June, the two 3G contracts were cancelled with no option of paying me back even though the services were never used. I am still being charged for the BIS though and the contracts are Samsung phones, what would I need BIS for. I see a change to Cell C for me and my 5 contracts in the near future.