I got the same reply from a collections account for Sprint. "NO PFD".
However, I am just starting out with repairing my credit but here is my game plan for this CA :
Send the letter asking for PFD anyway. Maybe you'll get someone else who doesn't know what they are doing?
When Refused, send second PFD letter with copy of a check that they can have if they approve PFD
When refused, Send third PFD letter with copy of certified funds check from bank, since there is more reliability involved with certfied funds...
The worst they can say is no right? Which is where you started in the first place...
Just an Idea...