NVIDIA only makes the chip, not the card. The card needs to be SLI capable, the chip is already capable.
If your card's manufacturers take 2 weeks to get back to you, you should have bought from another manuf.
Also, they should have a 1-800 number for customer support.
I bought my 6800GT from eVGA, and they responde to my emails next-day (if not in the same day) and their tech support is great (compare to the average).