I wish I talked to you when I first got my E320! One of the most humbling experience going to the dealer and asking how to open the gas tank. :-)
Repo man hope the tips help you out! Even if you finally get it to work...learn how to release the "fuel filler flap" manually. I was driving last year and my flap wouldn't open when I unlocked the doors. I remember the manual having something about it but when I came time to put theory into practice I couldn't figure it out. Luckily I was able to get the dealer before my gas ran and they taught me how to do it. For some unknown reason when I bought a new lock pin from FastLane the problem disappeared. It was a cheap part...maybe $5.
Let us know how it turned out.