unacceptable service then blacklist me

i have a hybrid acc which means by contract has a top up facility ex amount of data that can be used. making it a specific amount every month. i bought a ****ile from CNA at R299 with a 3gig data to be used within that year. i would top up my dogile via my bank account every month. then one day out the blue i get a billing via sms that i owe R2000 for 2gigs i queried this with no avail because the consultant on the other end of the line just said \well you've used the data so you gotta pay for it"i had to defend the fact that yes i was surfing but within my gigs per month with which i top up with and not at 5-6am in which the time frame was where the said 2gigs were used. My question was who opened my ****ile to allow this data without my permission. to add salt to injury Cell C then persisted to deduct from my bank account amounts of up to R6000 odd and they would do this twice a month because i would contact the bank to cancel the debt order. they would use the same ref no but change the cents in the eg R...50 then 49c. to clear all this up i tried calling cell c customer service cannot help. went to canal walk they couldnt help"