DONT TAKE OUT A CONTRACT WITH VODACOM

I have been over charged on my contract account. When i queried this i was told that a sim swop was done on my account over the phone. i must report it to Vodacom ***** division. No reply via email nor does anyone answer calls. i was then told to do a sim swop to stop the activity on the phone. I had to go to a vodashop and present my id and answer 5 security questions. i still have activity on that number even though i havent inserted the new sim. If you phone the number someone answers then hangs up. Vodacom says pay or we will cut your service. DONT TAKE OUT A CONTRACT WITH VODACOM.