While trying to get my sister the best rate with national, I have spoken with EC twice on the phone concerning reservations I had made - one rep suggested that I book with the EC contract code and then said "Oh, I see you're already getting a better rate with the priceless code." - When I called EC to add on a 'young' driver, she was putting in the info saying, "I see you're using an Entertainment coupon and the Priceless Vacation code . . ." - they seem to know it's being used and have no problem with it - how could they, you can log right onto their site through the priceless site. The only thing they were not able to do was combine a product rate code (WWEB) with the priceless code - it always kicked the concession fee back on - even though I still got a percentage discount - they said combining those two codes would not eliminate the concession fee and they were prohibted from removing it manually. All in all, priceless has given me the best rates so far !