Yes, I faced such an issue recently and ultimately got them to sign an agreement to change their name. We agreed on some terms allowing them some time to make the necessary changes to rebrand, etc.

Ideally you solve it amicably like this, as turning it into a courtcase is most likely out of your budget.

There's a lot to be said about this topic, but without knowing the specifics it's hard to give tailored advice. However, here are my 3 main points:

1. Definitely talk to a lawyer. Inaction is also action (see second point), so by definition anything you do or don't do might legally affect you and the future strength of your mark.
2. If you don't actively defend your trademark, you might end up losing the rights to it.
3. If your TM is registered with the USPTO on their principal register, and the infringing name is an exact or close to an exact match on a participating domain TLD (.com, .net, and many more) you might be able to file for a UDRP procedure which is a simple, fast, and low-cost way to have the registry transfer the domain to you as the legal TM holder. There's some caveats and you probably want a lawyer's help with this. Especially one familiar with the UDRP process.

I can introduce you to a TM lawyer. Email me ( [email protected] ) and I'll be happy to set up an intro.

Also happy to provide more advice in private DM on Telegram.