Vodacom is horrible to it’s customers

Vodacom is such a horrible company, I had a 36 month phone contract and it has ended in May when I try to cancel it I’m being told that I’m going to be charged for extra 2 months. I’m telling them that I’m no longer working and I have paid for the whole 36 months but they’re telling me that they won’t be cancelling my contract. This is going to affect my credit score.