I recently booked a full-size out of CRW for a week. I used the DL code K817600, which purportedly gives up to 25% discount. The fine print said that this discount would be applied at the point of returning the car.

Now, I am not one to expect miracles, but having received a discount of precisely 0%, I wonder whether this is perhaps not the greatest code in the world to use amongst the ones the airlines provide.