I paid 60% of the total estimate in June $4,365 which covered 100% of materials to install a tiled shower, bathroom floor tile, and materials to tile a kitchen back splash. The installer did not shim one of the shower walls correctly so there is a bow in one wall and he didn't install the tile edging at the top. The floor grouting appears to have efflorescence even though the grout packaging states this should not occur. The only materials left on site appear to be for the kitchen back splash even though the terms and conditions state all excess materials will be left on site unless you request them to be taken away. The installer left the site without a walk through of the bathroom or review of materials left - they will not disclose the quantity of tiles purchased to reconcile the invoice. I didn't realize he wasn't coming back to finish until 3 days later when I received an email with final payment due of $2,011. I immediately responded to the email/invoice that the work was incomplete and dissatisfaction with bowed wall and grout issues. I attempted to remediate via email for several days (with photos). My complaint was escalated to President who happens to be wife of installer. They proposed a separate project for additional cost of $765 to purchase and install an alternate tile edging from the original design and a $200 hold back credit from the original invoice for the edging they didn't install. They demanded final payment for the original invoice and full payment for the new quote to order within 48hours. They advised no further communication would occur until payment received or they would shut down the project. They would charge me an additional $300 to restart if I missed the deadline. Also stated I should pursue the grout issue on my own. Two weeks later I received a certified letter NOI to lien. What can I do to stop further action toward lien procedure with supporting evidence of disputed invoice/incomplete work when contractor refusing to remediate?