maybe the thaing to do is to flood that number with the same type of unwanted faxes they send out. I used to get faxes from a travel company that told me three times they would take me off of their list--they didn't.
I progerammed my office telephones (four of them) to call their toll-free number every five minutes and let them run for two hours.
Then I called the company and asked if they liked being annoyed--I got off of their list.