Bad customer service

I have a contract with vodacom on ***number, which I have been trying to cancel for the past 7 months, but I feel its not important for vodacom since they are benefiting from my money, I have been calling and also going to their stores every month since last year July 14 2020, and every time their consultant assures me that my contract will be cancelled and that they will refund me all my money, but this has been going on for months now, I don't know what to do now because no matter how may times I call or go to the store my problem is never solved, i am now out of options but to sue.