Faulty charges on account

In June I received my Edgars Statement, there were charges on my account (SMS Air Subscription and Airtime/Data Subscriptions) which I did not request or authorize. I contacted Edgars immediately, trying to get this cancelled and refunded. For the last 5 months I have tried to get these charges (totaling R642.29 to date) canceled and refunded. After 5 months (and countless calls and emails) these charges have finally been cancelled, but I'm still waiting for a refund. I have been called stating that I should pay my account immediately, as I will possibly be blacklisted as a "bad payer", they have also charged interest on this amount. I've been to the store trying to sort this out, and have been told I'm not the only one to who this has happened. What else must I do to get a refund on something that was clearly not my fault?