Contract cancelation from abroad.

I've recently moved abroad and had a contract with Vodacom for my cell phone. I've tried calling all their numbers and emailing them to make sure they do not continue charging my account after the contract ends and I haven't been able to contact anyone. They have continued debiting my account even though the contract ended in November. I contacted a person in store and they said they are unable to assist but provided a number I could call. I tried calling multiple times and by the time someone answers it uses up all the airtime I have as calls from abroad are really, really expensive. There's no email address that they respond to. This is absolutely despicable!!!