On Wednesday, 6 Jan 2016, I waited curbside for their Denver shuttle at 745pm, but it did not come. I called 2 times before their 8pm office closure and no one answered the phone, or was there a voicemail to leave a message. I finally reached the manager and he (and his staff) happily left me at the airport without a car. I will never rent from Ace again, and I suggest you avoid ACE like the plague.