I tried a similar thing going from Silver to Gold (all flights with KLM). I was a couple of thousand miles short from Gold on 31-Dec and then did HEL > HKG return with KLM in Biz in the first weeks of January. At the time, the website was still showing the miles I had accumulated in 2003 so I emailed them to ask if the flight in January could/would be counted towards 2003 (as the website indicated).

I got the "Rules are rules" response as well.

From the various posts on here, it's clear that they're not too worried about whether people actually flew with them in 2003 so why would they bother to bend the rules to reward those of us who did?!