You should definitely try to press your point, especially if you have it on the confirmation email. We had a similar situation at the Courtyard near SFO. I did a last minute check to make certain of the parking rate -- listed as $15 per night for non-registered guests and when we checked in they wanted $20 per night. I mentioned that the website listed the former and he said it was just changed the previous evening, but gave me the lower rate with no argument -- as he should have -- since my reservation was made months ago. I'm certain we would have paid the higher rate had I not mentioned anything.