What "rules"? That's what they are trying to do.. that's what a ticket exchange is... you book new segments in the PNR, price the change, then exchange the ticket (or relevant coupons) for a new ticket and add-collect new money + fee if applicable. This is most basic transaction that could be accomplished. I've been in ARD, I've seen it done before. It's very simple. I don't know what's going on here because I'm not party to the conversation, but to me it seems like AC has either hired people incapable and uninterested in learning the most basic of reservation system functionality, or has provided insufficient training, or more likely both of those.

For clarity to those interested in the basics of this:

- When you 'buy a ticket', you are creating a reservation (PNR) that holds the space on the flights in the relevant booking class, you price the ticket based on the desired fare, you pay money, then the ticket issued for those flights. The ticket is the payment for flight - that's the money.

- When you 'cancel a ticket', you are cancelling the reservation (releasing space on the flights back to inventory), and the ticket is then either refunded (in the case of a refundable ticket), forfeited (in the case of an un-cancellable ticket), or simply held open for use.

- When you 'change a ticket', you book space on new flights, price the difference in fare, if applicable, based on the voluntary exchange rules of the fare components in the original ticket (which can be varied and complex), then either re-validate the existing ticket (for certain small changes like date and flight number only) or re-issue part of or the entire ticket. Depending on the fare rules you may need to pay a fare difference and/or change fee, may get a refund, or may forfeit money.