Vodacom
Charged for BIS when it was cancelled

I cancelled BIS in April as I upgraded to a Sony phone. The first month I got a statement that was correct showing no BIS. Now I got a statement that had BIS activated again without my consent. When I phoned the Call Center they informed me that I will maybe not receive my money back. I want to know why you can just add services that where cancelled and then tell me that I will maybe not get my money back?