[donmcronald]

> If my company had charged someone and found there was no trace of it in our system, I would be very concerned.

I saw this happen to a business once and they never got any answers when they tried to engage their payment provider. It was a franchise, so they didn't have a direct enough relationship to really push the issue.

What would happen is a customer debit card would fail a transaction, so they'd redo it and it would succeed. Later that day the customer would be back to show them how they were double charged, but the merchant account only showed the successful transaction.

That was 5 years ago and as far as I know that money just "disappeared". It happened infrequently enough the business always ended up eating it.

To this day, I still want to know what happened.

In the case of the OP, I can imagine something similar. If ZipCar doesn't have any record of the transactions, why not get the customer to do a charge back? That way whoever ended up with the money loses it.

[actually_a_dog]

Although most of the other comments seem to want to blame ZipCar for doing something unethical here, I have to say this kind of "random glitch" scenario makes the most sense to me. No sane company would want to rack up disputes with their payment processor for such little potential gain.