I used to have no end of troubles with a TA when I first started flying slightly more than I used to. I'd check in advance with my TA who insists the ticket is valid only to be told at the airport that my "ticket" is not a ticket. It didn't help that my home airport, NCL just switched over to a third party agent who were utterly confused by my TA's bookings.

I decided to take responsibility into my own hands - I don't fly enough to justify a TA and plenty of advice on here for anything more tricky :-)