TRYING TO TERMINATE A CONTRACT!!!

I have been on the telephone for the past 45 minutes being sent from pillar to post by pathetic call centre agents. I am trying to terminate a data contract that should have been terminated when I took out a new data contract in September 2015 but have still had no luck in getting through to anyone who can help me. WHAT THE HELL??? I have still not been able to cancel the contract. I can promise Vodacom one thing, I will NEVER ever renew a contract with them or take out another contract - I've been with them for 16 years and I've now finally had enough.