They wouldn't issue a new ticket unless they got payment for the fare difference I would imagine. I understood from your initial post that the original ticket was issued with AMM-DOH as a surface segment. You then (after the issue of the original ticket) wanted to add a flight segment there. Even if it was unintentional from your part but you approved the flight reservations and paid for the ticket then you're probably facing an uphill battle. Hope you manage to sort it out, please report back.