They can't even explain what I'm being charged for

My contract ended in August, but cell c keeps on giving me data and debiting my account, I desputed the last debit oder end of October but they still gave me data for November, I was phoned manier times offered an upgrade but I refused to upgrade, I was paying 299 for the phone and 149 for data, when I phoned to enquire about the 327 that is being debited on my account I could not even get a straight answer as to where the amount is coming from, apparently its 155 for data and the other amount for router which I do not have or never received, please correct this and refund me all the money I paid after my contract was ended, I'm unemployed already, and now you still want to charge me R654 by the end of this month, you can take back your data if needs be, but correct this, I was a good client to you, but I'm no longer your client, stop giving me data and debiting my account.