I had a particularly difficult situation with Etihad recently. I booked a fully refundable business class flight using someone elses company credit card, and the website at the time told me to take a copy of the card and the persons passport when checking in. Fine, no problems with that. Then two days after booking, received an e-mail saying the booking was suspended until the cardholder presented themself at either Manchester or London airport, which they were'nt prepared to do. So we said ok, cancel it. They cancelled it, but it took 3 months to obtain a refund, and about 20 phone calls trying to chase this up.
A few minutes after I cancelled the booking, I used the same card to make the same booking on the same flight through Expedia, no problems at all.
On the positive note, Etihad is a fantastic airline to fly with, excellent service onboard, great as you wish dining service and good lie flat seats in cubicles.