per room guest

07:54 Mar 4, 2017 

Yes, that was the whole point of my comment: if EITHER theory is correct, one or the other word 'room' or 'guest' is redundant — which is exactly what makes me think that the writer may have had some other specific arrangement in mind when they chose this curious wording, and which is why Asker really needs to clarify with the customer.
The only pluasible theory I could come up with for having BOTH word in there would have been that the free credits don't apply to some other category of guests, i.e. ones that are not occupying a room... but that seems inconsistent with what little we know of the arrangements here: is it even feasible that this type of roomless guest might exist?

16:58 Mar 3, 2017 

if your theory were correct, then they would surely have said 1,500 credit per room, without adding "guest". It is the addition of that word that points to it being a credit per person

12:49 Mar 3, 2017 

I'd be very wary of guessing here, you really ought to check with the customer!

If it meant one credit for each guest in a room, then they'd probably say 'per guest per room' — then again, if it was really 'per guest', there's no need to mention the room at all!
Or, if it was ONLY for the accompanying guest, i.e. NOT for the principal winner, that seems rather unfair, and also, oddly expressed here too.
I suspect they possibly mean 'one per room' (i.e. however many guests are staying in it) BUT even this is far from clear in your ambiguous text.