Poor work and tiles missing - Waterproof it

At first, we were very happy with the work done by Waterproof it and it's owner, Chris Da Costa. However, tiling done near the end of the project, which was done on one of our balconies, was poor work, so we asked him to come and fix it. There was a 100 stories why he couldn't come through do redo this work, even though he gave a guarantee for his workmanship. He also has possession of tiles that I bought, that was left over, which he also promised to bring back, and has failed to do so, without a word. He stopped answering phone calls and emails. Please stay away from this guy.