Cell C

I have 3 data contracts with Cell C, i tried cancelling the 2 which i use for wi-fi and because it is a month-month contracts i can cancel them anytime as i wish. I tried for months to cancel the to sims that i use as wi-fi sims and they don't want to cancel them. Every month i receive high and all they say is that i must cancel subscriptions and when i have a look there is no subscriptions linked to the sims. My bill was suppose to be R400 a month and my bill is never less then R550 or more.