I'm thinking now that maybe you read your bill incorrectly. The way SL works the discount into the bill is by lowering the nightly price of the room. You won't see an extra line item (i.e. Discount 10%). That may be why you think you didn't get the discount.
For example, if you stayed in a room for 10 nights which was $79 per night. And your bar/restaurant bill came to $100.00.
Your bill would look like this (exactly off a past bill):
Tarifa/Rate: $71.10
T.C./Exch Rate: 520.0
The rate is listed as $71.10, which is exactly $79 less 10% CRT discount. That's where you find the discount. The rate is quoted in dollars, but they give you the exchange rate so you can figure out what it would be in colones. In this case, it's $71.10 x 520 = 36,972¢ per night (includes discount):
The charges will be in colones:
Room 369,720.00 ($71.10x520x10)
Restaurant 52,000 ($100x520)
I.S./ Service Tax 10% 5,200 (52,000x10%)
I.C.T./Tourism Tax 3% 11,091.60 (369,720x3%)
I.V./Sales Tax 13% 54,823.60 (421,720x13%)
Total ¢ 492,835.20
Total $ 947.76
I think I was an accountant in a past life.
