Sorry.
Almost this exact same thing happened to me. I was assured I was #3 at my local dealer when I asked to be put on the list back in October, so I didn't bother placing any other deposits. Later I come to find out that apparently some favoritism had caused me to slide from #3 to #5, and to add insult to injury they had sold an HEA car in the exact specification I had wanted apparently without addressing the list at all....
By the time I found all this out last month it was too late to get decent placement at any of the other dealers. Needless to say I'm pretty frustrated.
After they slipped me, I made damn sure to get my current placement in writing as an addendum to the sales agreement. (That's the only advice I can give you.)