I personally had success with this combination PFD and DV letter. It includes a contract for the collections agency to sign. While I could probably have gotten away with less, I feel better having the full terms spelled out.
The exact language will vary depending on your situation. You'd want to change it if the debt really is yours (without admitting that in the letter, of course). In most cases you'll want to send the DV letter separately first, but I had passed the 30-day limit in my case, so I was trying to make the best of things. I also included a check for the full amount, since I intended to pay and get the problem over with regardless of whether the pay-for-delete was succesful, but that may not be desirable in all cases. (Note that the agreement indicates that acceptance of the payment signifies acceptance of the agreement.) Of course, a collections agency will probably find it hard to resists a check that's in their hands.
