Customers who ordered L.A. Noire through 5/17/2011 and received a $15 promotional credit will be sent an additional $5 credit to bring their total credit up to the $20 level currently offered for new orders.
Yeah same here. I pre-ordered in May and I got $5 but not the original $15 I was supposed to get. I've contacted them, hopefully they can iron this out.
EDIT: I heard back within a couple hours from Amazon and they gave me the additional $15, although according to them I had already received it... In MY case, what happened is I have a "subscription" for a food item and they had applied the credit to that, but hadn't told me my subscription order was about to be placed, which I believe they usually do remind me of this. I believe I am now square with the L.A. Noire credits.