Extortion - unprofessional action of law firm

I receive a letter from a big name law firm with a claim that gave the impression that I have infringed that patent belonging to the client. The letter suggested discussion about "licensing arrangement".

I consider that the law firm had made the "request" without any basis and did not carry out proper diligence. By writing under their firm's letterhead, I consider their action to be tantamount to "extortion".

I checked the meaning of "extortion" and found the following explanation from Wikipedia. I will lodge a complaint to the Law Society that the lawyer is acting unprofessionally in "attempting to extort".

Extortion (also called shakedown, outwresting, and exaction) is a criminal offence which occurs when a person unlawfully obtains either money, property or services from a person(s), entity, or institution, through coercion. Refraining from doing harm is sometimes euphemistically called protection. Extortion is commonly practiced by organized crime groups. The actual obtainment of money or property is not required to commit the offense. Making a threat of violence which refers to a requirement of a payment of money or property to halt future violence is sufficient to commit the offense. Exaction refers not only to extortion or the unlawful demanding and obtaining of something through force, but additionally, in its formal definition, means the infliction of something such as pain and suffering or making somebody endure something unpleasant.