Extra billing for services i dont even know

I took a vehicle finance with Standard Bank vehicle finance in April 2016 early 2017 i notice they billed me extra and i called in to find out why. The consultant said it was additional fee for extended insurence and gave me another contact to call and cancel. I called and cancelled round about March. Later i noticed i was still billed extra. I called Standard Bank finance again and i was told the insurance was cancelled long ago and they would refund me that was in June 2017. Later i find out i am still billed extra and no refund paid. Please assist me cause now i dont know who to call or what to do beside just watching my money going.