MTN does nothing about YELLODATA complaints

I entered into a month to month subscription with YELLODATA and, when I did not need the service any longer, tried to end the agreement. They assured me of the cancellation of service, only for me to find that they kept billing me for several months after the cancellation was processed. They come up with all kinds of excuses and I contacted MTN in this regard since YELLODATA claims to be affiliated with them. MTN outright refuses to help because YELLODATA is a separate company selling "MTN" data pakages. I have now lodged a complaint against both companies at ICASA.