OMG I can understand you being totally pissed. It IS an invasion of privacy, and also disrespectful. You asked to be left alone by becoming a DNC and they should honor that.
But if it is an elder - then the rules don't apply to them (or so they believe). You should apparantly be grateful they sent you this letter so you can be "welcomed back into the flock" smiley: sick

Andria's letter is very good, but a little too polite for my liking! I think I would be a little stronger in my words, not rude just firm. You could also put that you are an apostate. This might do the trick, they probably won't want to come near you with a barge pole.