Non - cancellation of contracts

I had 3 contracts with vodacom, whereby 2 of them have expired already early last year, Ive been trying to cancel since last year. Every time when I call the call centre the consultant will behave as if they are willing to assist at the same time trying to persue me to change and they will promise to offer a better package, and when they hear that I am adamant I want to cancel both contracts, towards the end of the call , they will tell you they no longer hear me, as a result they drop they wont call or cancel as requested. I am honestly fed up with this service provider because the money they are taking its a lot, in stead I feel that I am being *****ed because it seems their consultant are having same behaviour, which is so annoying, dealing with consultants over the phone was suppose to be stress free, but with vodacom I am not happy at all, ive been with this service provider for way too long, I think its time to change, because they dont value us anymore. The only thing that they do best is to share our contact details with their contractors that will annoy us.