Pathetic service from Vodacom

Vodacom is just not canceling my contract. I have been trying to get this contract canceled. I have been dealing with this query since August. Early December I spoke to a consultant who said that someone will pick up the device and then only will they cancel the contract but that's never happened. I keep complaining about they are are still not canceling. This is the worst service I've ever experienced in my entire life.