Hello. My neighbor has performed many plumbing jobs for me. I hired him to plumb some fixtures and let him know that I would be providing the materials needed, which also included instructions for proper installation of the fixtures. He chose to use his own materials, ignore the instructions, and in doing so, rendered some of the functionality of the restroom unusable. I have since paid him, but tried to negotiate a refund for the improperly performed labor, or a fix at a discounted labor rate. He agreed to neither options. I have considered disputing the charge on my credit card, but he has since threatened to file a mechanic's lien against me. Does he have legal grounds to do so if he performed the work improperly and I dispute the charge? Thank you