Vodacom auto-renewed my contract and won't cancel it after I emigrated

I emigrated 3 years ago and had an active Vodacom contract which I continued to pay to term. Once my contract came to an end, they auto-renewed it without telling me, and have been charging me R438 pm since August last year (2021).

I have emailed them on numerous occasions but they have become unresponsive, and their manager who promised to call me to discuss never did (she couldn't seem to understand why I wouldn't just call the call center from my Vodacom number, despite living in the USA and not having used that number in 3 years).

This is ********** theft, and the lack of urgency is extremely annoying as I am having to try engage with them while overseas.