I have asked three times to be added to the do not call list, plus I called and left a message at the hall, they still come. Of course, there is no excuse for shooting a gun over it, but I can relate to his frustration. I work from home and it is very annoying to be interrupted, often I am covered in paint and don't look presentable, but if I ignore them they just keep coming back.Ultimately, you are dealing with a bunch of amateur volunteers, some children, with a very haphazard system of recording info ... scribbled not on a piece of paper that probably get's lost or discarded by someone along the chain.
Although they can seem annoying they don't usually call that often and i's not really onerous to answer the door now and again.
But yeah, you can't not-answer because you don't know who it is ... I wouldn't want to miss out on the opportunity for Girl Scout cookies !!
I agree with Simon, you don't want to miss the cookies. I can think of two methods that might get there attention
1) glue your letter to a piece of plywood, go to the hall on Saturday night and screw the plywood to the front door. Use about eight screws so they have to spend some time getting it off.
2) That may raise legal issues (although it wold be fun) so hire a process server (cost starts at about $35 here) and tell him the best time to catch somebody is about half way through the Sunday meeting.