Struggling to cancel contract

I initially signed up for the black Friday fibre deal at the end of last year 2022 when it was on promotion but there was a delay in delivery of sim and device, and when it eventually arrived, I cancelled it shortly after and asked for the device to be collected. It was collected but my contract was never cancelled. It's almost April and I'm still paying for a contract I have not used. After numerous calls to Vodacom over the past couple of months, I'm still left with no resolution, and I still get billed for it. PLEASE HELP.