I am a subcontractor that has finished a job. We are having trouble to getting paid our final payment from the client.
You may have missed a deadline for filing a mechanic's lien for a progress payment, but may still have lien rights to the 10% retainage that the owner is required to withhold.
You should consider preparing a letter to mail by certified mail, return receipt requested, to the general contractor (which I assume is your client) to set out the facts and to demand the relief that you want. Attach your outstanding invoice and photographs to document your completed work. Make sure that your letter is professional and business like as it may be evidence later.
If your claim is less than $20,000, you can file suit in small claims court using your letter as evidence
Retain a construction attorney to evaluate your legal position and to provide advice.
Good luck.