You could try doing it yourself: On the right side under the car, look for the drain hose, approximately below where you perceive the under dash AC unit to be.
Use tubing or something rigid enough to move up the drainpipe but not too hard as to hurt something.
My guess is a dealer would charge either 1/2 hour labor or possibly do it for free.
Call your store and ask to speak to the shop foreman. Often when they are not too busy they will help people out.
Keep us posted,
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)