Anyone heard of this debt collector?

Boy, I think I'd be careful on that one - especially when he says he's 'fishing for information' about you. Sounds like a scam to me!

But, on the other hand, this could also be a debt collector. It wouldn't hurt to answer one of his calls and find out who he thinks he's calling, and what debt he is attempting to collect...and what "complaint" he has about you that he's responding to. I've never heard it phrased quite that way before.

If it is a debt, make sure you obtain written validation by sending them a validation letter (get his address while he's on the phone), and go from there.

You don't have to tell him anything. If they'd planned on filing a complaint (with the court), they should already have had enough information about you.