Taken for a ride

We signed a contract with Martin Els to complete our house in May. We had already built the basic structure. He said the project would take 3-4 weeks from start and we paid a 40% deposit. Work started on 3rd June and by mid-August he had worked 5 days only and didn't even complete the outer walls. The last time we saw him was 3rd July. We messaged and called regularly but always received an excuse of why he couldn't be here. We gave him an ultimatum and asked for part of our deposit back. Nothing received as of 3rd Sept, and no feedback from Martin. We hoped for a good experience however, it has ended on a bad note. We do not recommend him.