Money deducted incorrectly and after 3 weeks still waiting to be refunded!

ADT has really disappointed me once again. After receiving terrible service, I cancelled my contract with ADT. On the 1st Dec ADT incorrectly deducted just short of R700 from my account. I have phoned numerous times and was promised each time I would be refunded very soon, and I am still waiting. I get promised to be phoned back and each time do not get phoned back. I really need this refund with christmas coming up and it seems it is not going to come anytime soon.