The shuttle picked me up immediately when I arrived in their lot, though when I returned to SFO I saw it driving off as I walked out, so I did wait 20 mins on return.

I don't quite understand how you pay. The shuttle driver gave me an orange validation card, and if I read it correctly it said to enter it after the parking ticket, which I did. Once I did that, though, the amount due disappeared and the gate opened. Worried I might get stuck inside, I exited. I never entered my credit card to pay.

Tried to e-mail them on their web site and it bounced back. I called and the person I spoke to transferred me over to reservations which gave me a voice mail tree with no option for customer service. I'll call again during the day time.

What am I doing wrong here? Also I noticed their rates had changed from $9 a day when I arrived to $7.50 a day when I left.

edited to add: I called this morning and it's sorted out and they'll charge my credit card. The phone is answered by the Hilton and they sent me over to accounting to resolve it. They needed to know about what time I left. I was charged $6.50 plus tax. The rates really do seem to fluctuate. I'll be back there tonight on a Florida trip.