A few months old but nonetheless interesting. Expedia's web form looked like this:
Credit card number*:
Some costumers, instead of leaving the optional field (which was Company) empty, they entered their bank name and continued with the bank address instead of theirs. And the transaction could not be completed as the address did not match the card holder's address.
Apparently this cost them $12m in loss.
The personal details form and the billing form are now separated and divided in two steps.
1. The first form (passenger's info):
2. The second form (credit card and billing address info):