Yep, if you go to the Becker web site, there's a toll free number to their parts department in New Jersey.
Believe it or not, Becker considers the radio code to be a radio "part". They can look it up by radio serial number and the charge is $30.00
Didn't want to pay the 30 bucks, so went back to the Mercedes dealer again... sure enough, they had given me the wrong code. They re-checked, gave me a different number, and now everything works.
Thanks, KenP