Manufacture & install burgler proofing

My husband & I own the property 936/937 Eynsham Road, Henley on Klip. We asked the tenant to obtain a quote for the manufacture & installation of burgler proofing. She obtained a quote from Driehoek Staal Werke for R21,000.00 which we accepted. He said that he was very busy, but would get the work done within the month.<br> We then paid the R21,000.00 into the tenants account (Lana Nel) on 13/11/2013. She then paid the amount into the Suppliers account, (unfortunately before the work was completed) Since then, Lana and we have been phoning him on a regular basis, but he just makes promises that he does not keep. We even went to see him in Sasolburg, and he explained that he had been having problems with labour, but that the work would be completed within a month. Nothing has been done, still just promises that he does not keep.<br> We would like him to either complete the work, or refund the money, with interest as. Thank you for your help.