It is a mess. I'm a Realtor and former contractor-Builder. The Realtor should not have had his name on it. Period. You should not have accepted a contract and performed work on a home where you didn't have an enforceable contract. Not Ever. Only home owners, or duly authorized agents (with paperwork to prove it) could contract and committ the Home Seller. I'd address your complaint to the Agent and his Broker in Charge, hopefully he works for a bigger firm. Before calling a lawyer...
Write a certified return receipt requested demand letter, with a demand date- a resolution must occur by___ or else
File A complaint to the real estate commission
An ethics complaint to his local association
And a court case
and then be prepared to compromise. You need to learn from this, because best I can tell you have zero lien rights, and a contract that will cost you money to try and enforce. Your position is not a strong one, but neither is the Agent's. I suspect there is a resolution long before court.
You will be amazed at what a certified letter can accomplish, and send his Broker in Charge one too...
Good luck and do speak to an attorney about contract law-- I'm guessing your contract doens't have a senetence that says, '"In the event of default,... to pay reasonable legal fees."? Without this language, small contracts are frequently unenforceable because of the high cost of litigation.