credit union dropped the ball

[94caprice]

What is the name of your state (only U.S. law)? Tn.
Last year my son traded a 1988 Honda car to someone for a 1995 S10 truck. The guy had a loan with a credit union. My son & i went to the credit union to do the transaction. The credit union released the lien on the truck & gave us the title for the truck. We then left & all was good. Last week someone came to my house wanting my son to get him the title for the Honda we traded last year. It turns out the credit union dropped the ball & never sent the title off. The guy who had the loan defaulted on the loan. The credit union resold the car to a 3rd party & told him to get my son to get the title for him. My son went to the DMV & asked for a lost title & got a clean & clear Lien free title in his name. The credit union says they gave the title to the guy we traded to & he never did anything with it.
The car isnt worth much & thats not the issue. The problem is the credit union should have sent the title off with them as the lien holder & received the title back & held on to it until the loan was paid. They are blaming it on the guy & said they cant get ahold of him. The funny thing is he came to my house 2 weeks ago to talk to my son & his parents own a carwash 2 miles from the credit union, so finding him is not an issue. I am more upset in the legal ramifications that could have been had something happened. The credit union has a copy of the back of the title that my son signed, but i have the title.
What can i, or should i do?

[94caprice]

Sorry if i posted in the wrong section. I really wasnt sure where to post.

[Zigner]

What can/should you do about what? I'm not sure I understand how/why you (your son) even got involved in the business between the Credit Union and the other guy...