Why is Vodacom still deducting money after the contract is finished

Its the worst service provider i had to deal with. Why do they still deduct money for a stupid data line that you didn't sign up for long after you finished paying your contract.

I finished my contact and called them to ask if they could close the line and stop deducting money from account. The lady I spoke to did that and 3 months later I get a statement and I owe the R450 and I call them to find out I was sent from pillar to post. Eventually spoke to someone they said they will investigate and get back to me this was now the beginning of the year its the 18th and I am still waiting. Besides that i tried to go to the store and sort it out I was even willing to pay and close the account they said they cant help I need to call the office, They same stupid number to call where I do not have joy

Is there an ombudsman that can help sort out this mass because my credit well being is compromised

I beg you never use Vodacom for anything you will be sorry