Dealer can't help. It's an add on (though offered by a dealer) that is not supported by a dealer. Best I have so far is a locksmith-trial and error.
Cross bars are close to $200.00 each; that's why they're locked. :-0
Go to a Chevy dealer and ask for the service bulletin for the roof rack. In the bulletin there is an email address, send them your name and address and the key code and they will send you 2 new keys.