A friend of us was employed by a pest control company (company A) until they fired him recently over some stupid mistake. When he worked for company A he had solicited us to use this company.
Now he got a job at pest control company B and offered us a better deal if we would switch to this company which we did.

Now we received a certified letter from an attorney working for company A which basically says that they have information that he solicited us to use company B which is in violation of a Covenant Not To Compete which he executed in favor of company A and they were going to commence legal action again him and they were going to include into such action any other parties (such as us) which after receipt of this notice continue to assist him in interfering with their clients contractual rights. The letter goes on saying that they hope this is a misunderstanding and if so they want a written response.

What if anything should we do? Should we respond to this at all?

What sort of a contract did your company sign with Company A in the first place? YOu need to refer to that contract and read the fine print that says you have to use Company A for such and such period.

I think they can sue you. I don't know that they will win. I would have to read the law in your State as well as the language of the non-compete.

They certain can sue him and win.

Why would you continue to work with this guy, even at a reduced rate, if he disregards signed contracts? What he did to them he will next to do you - throw you under a bus.

I would expect your records will be subpoenaed as part of the lawsuit against him.

What State?

Florida