Not to put too fine a point on it, but a rock bottom refundable AZ ticket will run just over $2,900. Bear in mind, this is about refundable to original form of payment, not flexibility to make a change. I am certain that some research might bring a routing somewhat cheaper. But, refundability comes at a steep price.
If AB is not operating the return and is unable to be acommodated, he will then have a valid chargeback and can then look for a cheap ticket.