Huge bill

I have been with Vodacom network for quite some time but recently I am struggling to cancel most of my unused data . I have for several times phoned them as the outlets in Soshanguve, kollonade and Mabopane were unable to assist me so I contacted their call centre and for several times they said they have removed some of the things I don't need in my contracts but come month end I again have that huge bill . this time Vodacom has really disappointed me and I can't cancel those contracts as I can't afford to pay for the hand sets that I received.