anybody know about "free" updates to Navigation DVD?

I bought a new E320 wagon last August. I has the Navigation system and the DSVD is marked 2-2004 (Feb 2004)
I inquired at the dealership what the current DVD was (since I have
noticed errors on "newer" roads). I found out that there is a 2005 version (2-2005). I was prepared to buy it... but...
I was told by a parts guy at the dealership that i qualified for a "free" upgrade since I got a 6 month old DVD with my car, and that the car was under 1 year old. he told me to call 800-for-merc and to ask for the "complimentary upgrade".
When I called MBUSA, they acted like I had asked them something in greek. They told me they had no idea about what I was told. They said they had no such program!
Am I being told things wrong by the parts buy? Or did I get a bad phone rep at MBUSA?
I called in on Friday to the dealership and talked to my sales rep. I asked him to look into it, but I have not heard back yet.
Anyone know about this program?
thankk in advance

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