andrew,

I suspect the letter from your attorney will be enough to dissuade them from hounding you any further. I had a problem with an insurance agent who notified me that he would have to switch me to a higher insurance because the law and I couldn't agree on the posted speeds and that the rate would be 4X of what I was currently paying so told them to pull my policies. I was done with them and would find another insurance company. Well six months latter I get a letter from the insurance company saying they were turning me over to a collection agency so I went to a lawyer and had him send them a similar letter; the problem went a way without any mark on my credit report.