DEAR TRAVEL TROUBLESHOOTER: I missed my flight from Edinburgh, Scotland, to Dublin because of Aer Lingus’ lack of staffing. There was just one member of its Edinburgh Airport staff to check in passengers for all flights that day. This lack of personnel resulted in me and more than 20 other passengers waiting over 3 hours in line to check in. We all missed our flight because of this, and I also missed my connecting flight to Boston.

Aer Lingus wrongly charged me to rebook my flights and get home. A representative told me that I could get a refund by submitting an online claim. I have been contacting Aer Lingus for the past six months, and I am still not getting anywhere with their customer service. I also emailed their CEO and was just passed to another customer service rep who takes weeks in between correspondence to email.

Can you help me get the $1,200 in rebooking fees refunded?

— Catriona Garry, Norwood, Massachusetts

ANSWER: Aer Lingus should have had more than one employee at the airport to check you in. But it didn’t, and as I reviewed the paper trail of correspondence between you and Aer Lingus, it’s clear what happened. Your departure was scheduled during the busy summer travel season, when airports are crowded and flights run at full capacity. And it looks like the sole employee who checked you in worked for a third party called Swissport, not Aer Lingus.

And there was another complicating factor: The first leg of your ticket was not on Aer Lingus but on Emerald Airlines, a code-share partner. According to Aer Lingus, you didn’t have a connecting flight to Boston on your itinerary, but it’s unclear how that could have happened.

You missed your flight to Dublin because of the slow line caused by a confluence of events. But when you didn’t make it to Dublin for your return flight to Boston, Aer Lingus considered you a “no show” and canceled your reservation. (All airlines do this, so it’s not just an Aer Lingus policy.)

When you applied for a refund, you received a form letter from Aer Lingus that reminded you to show up for your Emerald Airlines flight on time:

“Our recommendation is that all guests arrive at the airport 2 to 2½ hours in advance of departure for flights within Europe and 3 to 3½ hours in advance of departure for flights to/from North America, regardless of whether you have checked in online or via mobile,” the letter said.

Obviously, Aer Lingus hadn’t read your account. You were waiting in a 3½-hour line, so you had hours to spare at Edinburgh Airport.

You did a great job of keeping a paper trail and eventually appealing to the CEO of Aer Lingus. It felt like Aer Lingus was trying to wear you down with form responses and empty promises. The airline relied on a third party to provide adequate staffing in Edinburgh, but this third party didn’t meet its obligations. So, Aer Lingus is still responsible, even if you’re flying on Emerald Airlines.

The takeaway? If you’re making a connection, be sure that your itinerary is connected by having the same reservation number. Otherwise, if you miss your first flight, or if it’s delayed, you could be in big trouble.