Help Getting a Builder to Finish - 12 months into 3 month project.

I have a builder doing a renovation here on my house in the Dublin area. He was the most expensive quote but was very impressive and we agreed a 3 to 4 month timeline but I stupidly never put that in writing. He removed our central heating weeks into the project as it due to go back on 12 weeks later, we are now 12 months later with no heating and living in a bedroom with no kitchen for the last 4 months! What do I do?? This asshole has been paid in advance all along and will be asking for the final 10% when it is finished (whenever that is). I'm thinking I'll have to make it a legal matter asap. I understand delays happen but this is gone past a joke. I've tried being nice, paying in advance, shouting but nothing works. Any advice is greatly appreciated.