Im probably gonna get crap for this.. but have you tried the collars that stop the barking? However i would only use that as a last resort.
If your home a lot, I would go around with your pup when they go potty, that way you can tell them No! when they do it.. I dont know, thats what I did, however I work at home and I know not everyone has that luxury.
Good luck with it though! I would do something quick if the association is sending you letters about it. I also know what is like on the OTHER side of this story because working at home and all, my neighbors large dog would not SHUT up and I didnt want to, but I had to complain to the association because the owners would not listen.
good luck!
