Untrained staff that doesn't know ticketing rules
On ticket reissue during a cancellation I lost access to the correct seat map. Airline said the issue was with the travel agent, they can't fix it. Called Underpricer, none of their agents spoke English well, didn't/couldn't understand that the ticket was likely out of sync because of the change and the seat map showed the wrong cabin. They didn't even know what out of sync means. Use another travel agent or book direct where possible!