Unreachable bill increases on blocked sim

I have lodged a complaint in November about Vodacom sending data on my blocked sim card and busy increasing on the bill. I have never had any help to date. I was owing R586, after i made arrangements, my bill went from R586 to R1834.15 to within 2 months . I need them to tell me how did they get to that amount and why im i charged for services not received.