Vodacom Data Contract

My data contract was cancelled in June 2020,i am still being billed for this contract. I have phoned cancellations nearly every month to ask why I'm still being billed, they advise it will be cancelled and I will be refunded my money...... It is now January 2021 and still being charged for this contract!!!!!!! Everytime I phone and ask for a reference number I'm being told they don't have one I'll receive an sms which I still haven't received since last year!!!!!!! This is *****ing and I want my money back.