Vodacom
BIS not cancelled

I upgraded to a non-BB contract 2 months ago (migrated from BB to Android). Today I noted that the BIS was still activated. Upon contacting customer service I was told that I should have requested the deactivation of the service. How can I pay for a service included in a specific contract that I cancelled as required? BIS was deactivated, but I paid for it the past 2 months.