We had just one sale to our credit during the first round of the ambassador program that started in July and ran to October of 2015. We had fully planned to use that $1000 toward our Model X which we'd ordered at least 2 years prior to the program. Based upon both a press release and the original email:
{snip}From now through October 31st, if someone buys a new Model S through your link (removed link), they will get $1,000 off the purchase price and you will get a $1,000 credit in your Tesla account, which can be applied to a future car purchase, service charge or accessories.{snip}
Well, apparently, they never intended to allow the credit to be used toward a Model X, only toward Model S, and now I think even that they don't want to honor. I pushed back modestly but was told that our Regional Manager confirmed that they never intended and would not allow the credit to be applied toward our Model X. It wasn't worth a court battle as I'll need new tires on the Model S soon enough and the credit can, apparently, be used for that. But if anyone is sitting on a bunch of referral credits and expected to use it toward a Model X (or maybe even an S), you very well may be unable to do so.