Bad service

I would like to express my disappointment at Vodacom, on the 28th December 2020 I called Vodacom to cancel one of my contract which ended in December. The agent I spoke to in the cancellation department assured me that my contract was cancelled. I was surprise in Jan when the billed me for the contract that I cancelled for the amount of R230.00 I disputed the amount thereafter and I was promised that it will be refunded. After few days gone by I realized that the refund was not done, I then approached my bank to reverse the debit order. I'm now shocked upon receiving notification that I owe the 330.00 now they added R100.00 on top of the 230.00 that I disputed. I've been their client for over 15 years to be treated in this manner. Each time I call Vodacom regarding this matter I'm being send from pillar to post. All I need is for them is to ensure that the contract is cancelled and the amount reversed.