Refuses to refund money due to his non-delivery

In January 2015 I paid a deposit of R21,000 for doubled glazed aluminium windows. Week after week he promised to deliver. Him and his wife promised that if did not have the windows by the long weekend in March then they would fully refund my deposit and I still waited. Every time Marius promised that the windows would be delivered I took leave from work or arranged time off and then he wouldn't bother to pitch up or answer his phone. Eventually he said that I should rather find someone else and that he has arranged with his supplier to get a PD cheque back in lieu of the money. He even offered to help me find someone else. I did find another supplier but I cannot pay the balance of the money because Marius refuses to give me my deposit back which means that I now forfeit the second deposit too. The supplier is not willing to wait indefinitely until I can pay the balance of the money.