Was not refunded twice

I am very angry at This company I rented a car in late July and I never got my refund . I went to Herts O.R Tambo and they made a phone call for me which the end results of the call I was told they can't help me with my refund because I lost the rental slip ontop of that I had many charges . On the 30th of October I went to rent again , I had no choice as the car I could Afford was Group A and they were the only company with group A available . Today it's the 08 of November I still do not have my refund back . I don't know what to do because what is worse now is that they don't answer their phones 😭😭😭