Cell C ignoring my cancellation notifications

I had a month-to-month agreement (NO set contract) with Cell C for more than 2 years which amounted to R105 per month. This agreement meant that I could cancel at any time. In November 2020, I left SA for Europe. I no longer use the SA number or sim card. I have advised Cell C on numerous occasions (via email) to cancel my debit order from my Capitec account. They, however, choose to ignore my emails and proceed to deduct the amount they claim I owe them (which is escalating every month). Each time I have to dispute/cancel the debit order with the bank, I get charged a fee for this. This is becoming really frustrating! Why is Cell C so quick to agree to this agreement but don't stick to their end of the bargain? I have escalated it in January to their Consumer department of ICASA, but my request is still ignored. Wake up Cell C - you cannot charge me for a service I'm NOT using!!!