Do I have to provide Pressler & Pressler with my personal information?

Alright then you want what I suggested above, the statement, the agreement and the right to collect. You could also call visa and ask them who is handling your account or who they sold it to if sold. That way if they say another company, you have even more solid reasons to ask for the validation...since VISA claims differently then they do (they may have bought the debt from another company and so on and so forth).

Well, I have prepared the letter & will mail it return receipt requested. Then see what happens. I suspect they will not be happy about this, but oh, well, tough you-know-what.