It all depends on the specific transaction. But, as a general proposition, the TA only holds the funds for a very short period of time (or none at all). In the ordinary circumstance, one contacts the TA, it contacts the carrier for approval, and then issues the refund with the carrier's approval. Now, it either cannot get the approval because it is denied or the carrier is overwhelmed and does not respond. Thus, if the TA issues a refund, it is doing so with its own funds. For a low margin business, that means funds run out quickly.

This is where the chargeback comes in. If it is just an unflown air ticket, it is easy enough because the amount in question is the amount paid. If the ticket has been partially flown or it is a package, apportioning what is the air ticket can be harder. More importantly, some jurisdictions -- not the US -- do not permit partial chargebacks. My thought is if one cannot readily determine the amount, one does one's best and provides a justification for the amount.

The consumer has no way of knowing who holds the funds and at what point. But, the carrier and the TA can sort that with the card issuer and leave the consumer out of what amounts to a back office transaction.