Worst network to try and cancel a contract

Vodacom is definitely the worst provider to try and cancel a contract with. First they messed up my upgrade, then they messed up the reversal of the upgrade by not changing back the dates on my contract to show that it is due for an upgrade again, then when I had enough of them they couldn't just cancel my contract. Now, after 6 months of paying them for something I no longer want, 6 months of calling and asking them to cancel, I have cancelled the payments and now suddenly someone can pick up the phone and call me to insist I pay for a contract I have been asking them to cancel