there was a phone number i called that was printed somewhere within the credit offer letter. it is broad spectrum credit offer refusal - not just for the company that sent you the letter. you can register for either 5 or 10 years off the list of preapproved offers for credit cards, insurance, and the like. i was able to also register my husband when i called.
good luck!
it's worked for us to really cut down on junk mail.