Fed up with Yello Data

I have cancelled my contract in March after they deducted much more than the agreed upon amount. Then they proceeded to deduct another R500 or so from me the next month. Then they have been deducting R99 per month to date. Every time i call or mail them its a different story. I am so fed up with this company. And all that MTN does is send this response "Hi Jeanine,

Thank you for your post.

Kindly see the below contact details for YelloData for further assistance.

Contact Details : *** ********** Operating Hours Monday - Friday: 9am - 5:30pm Saturday: 8am - 1pm Closed on Sundays & Public Holidays

Regards Tsholo Social media Team" I mean really now! I need help with getting them to stop deducting from my account.