In my opinion, there isn't one.
BY mistake I double-ordered a book sold by Alibris itself.
Any attempt, via web, mail, telephone, curses, was fruitless.
Ridiculous automated reply (contact the seller - the seller is them).
email only and would not refund my money on an order that never came.
No one answers. Not unless you are ordering a book. No one answers if you want help with a refund. You just get a recording.