After a stint in the collections industry I roll my eyes everytime I hear the "H" word. You must remember Troubled mind it is not Harrassment till you tell someone to leave you alone. After reading your other posts I believe this is the first time you have done this. I am very proud of you and I think your letter is perfect. You need to vent directly to them. Yes they will take is as a DA letter because you are refusing to play by the "clubs" rules. Don't get so hung up on who is in control, you are. You are finally taking control by doing this. There will be consequenses for doing so but it looks like you will be just fine. I know it's hard but don't dwell on the old friends and connections and being villified. I'd simply but up a sign on the door saying no JW's or solicitors that along with a phone call or letter like the one above should do it.
-Cage