Answer: Continental shouldn’t have charged your travel agent $500 after your flight. And even if it had, you shouldn’t have been dragged into it.
Let’s take these issues one at a time. The charge from Continental to your agent is referred to as a debit memo. Airlines send them to travel agents when they’ve booked a ticket incorrectly (or, as they often like to say, illegally). The problem with these memos is that they’re arbitrary and sometimes unreasonable. If an agency doesn’t pay the fine, it could lose its ability to write an airline ticket.
You’re correct in your assessment of the airline’s position. Airlines (not just Continental) expect agents to know their rules, and when they violate them, air carriers are quick to demand that they pay whatever penalty they see fit. I would have no problem with this, as long as airlines were clear about their rules. In your case, it appears Continental’s employees misinformed your agent.
Should you have forked over $500? No. You used a travel agent and paid a booking fee because of his expertise. Also, you paid your travel agent for the tickets, not the airline. I can certainly understand why an agent might be tempted to pass along a debit memo to a client, but in almost every circumstance, I don’t think the customer is responsible for a fare difference or penalty. It’s your agent’s problem.
You might have cleared this up by sending a brief, polite email to Continental. I list the names of customer service executives on the On Your Side wiki (http://onyoursi.de/wiki/). A written query might have initiated a more thorough investigation, which might have revealed that the agents to whom you and your agent spoke gave you incorrect information about the change fee. Most airlines record every conversation in their call centers, and can listen to what an agent said and then make a determination.
I contacted Continental on behalf of you and your travel agent. Your agent contacted you shortly after that, saying that Continental had reversed the charges.
(Photo: martin toy/Flickr Creative Commons)