Construction Money Owed

I entered into a construction contract with the owner of Chia Group, Aluwani Netshia to build a house in Blue Valley. I paid him all his construction fees. I also paid him upfront for buying materials and building expenses to the tune of R500 000. He only used half of the money and never completed the construction work, running away with rest. He is not trustworthy and has been refusing to pay me back for the past 2 years.