A client is in the following situation:

He hired a contractor for repairs on his rental property for a one-time job. He received a standard contract which addressed the contractor's responsibility for paying Federal and State taxes. The client forgot to get a W9 until shortly after the job was completed. At that time, he sent one to the contractor. No response.  After a month he texted the contractor and politely asked for the completed W9.

The contractor responded by lying about their agreement and attempting to extort the taxpayer, saying "that was a cash price" and "I have to send a revised invoice for an additional 15% to fill out a W9." Everything the contractor says about their arrangement is an easily-proven lie. The taxpayer has the invoices and proof he paid in full, by check and by Zelle.

He is still trying to communicate but let's say he does not receive the W9.  Does he send in a 1099 with the word "refused" in the TIN box?  Should he gross up what he paid so it includes backup withholding and pay the backup withholding?

Is there any recourse against the contractor? I realize that isn't a tax question. Unless there is a tax-related remedy?  The taxpayer got him as a reference from someone he trusts. The taxpayer deeply regrets not getting the W9 before hiring the guy. If he knew he was so unethical he would not have hired him. 20/20 hindsight.