Debit orders continue for a canceled contract

I emigrated and before I left in May I called in and I canceled my contract. To my surprise I was debited in June and then again in July. I sent emails with no response. I can't call on the 083 number as I'm not in South Africa. I can't even reverse the debit order because it's above R500. This is absolutely a ****. Very frustrating and unfair. I sent emails and noone responds. I didn't expect this from a big Multi national company like MTN. Surely when a contract is canceled, I'm not even in South Africa and not using that number yet I am getting debited. I am very disappointed. I don't even know what to do or how I can escalate this. It's unacceptable