About a month agao I was also unable to get the file from the Dynavin website either, however in the end I found out I already had the most updated version. Dynavins ROM is not that good.
I purchased one that I think was called ///M3 Revolution for about $30. It is worlds better in both preformance and functionality. It was posted somewhere on this forum. On his website is the most updated version. If I recall correctly the newest version was 1.5?
I'm not sure how much you paid for your unit, but based on mine, it was a no brainer spend the extra 5% ($30) for a ROM that is 2+ times as good.
The developer said he wants to update to Android 2.3 however he can yet enough info from Dynavin. I hope the give it to him soon to resolve the 2.2 Wifi connection issues in Android itself.
Hope it helps,
PS...Dynavin's customer support is not that good. If you still need the stock ROM I wouldn't rely on them. Google or another forum member might be your best shot. Sorry, I don't have a flashable file to send you.