How is it that airlines keep screwing up simple things like company policy and established TSA rules?

The latest travel blunder belongs to American Airlines. When Sara showed up with her husband and young son for their flight from Boston to Arizona, the gate attendant stopped them for having too many bags and tried to charge them a $150 fee to check a cooler filled with frozen breast milk.

Salow told ABC 15 that she and her husband had shown up with four carry-on items: a stroller, a diaper bag, a backpack, and the aforementioned cooler.

"I'm like, 'This is a diaper bag, which I thought was exempt; [that backpack is] his personal item and we have the cooler -- I didn't have a personal item,'" Salow told ABC 15. Most airlines -- including American -- allow passengers to travel with one carry-on and one "personal item," which for most people usually amounts to a small suitcase and a backpack, briefcase, or purse.

Additionally, Salow told the news station that she'd looked into what she could bring with her ahead of time. American Airlines exempts certain items from the carry-on policy, including strollers, diaper bags.

Further, TSA rules exempt breast milk from the "no liquids" policy, and American recognizes that -- though ABC 15's report notes that the airline's website didn't specifically list breast milk as exempt until Dec. 14.

Despite all of that, Salow told ABC 15 that the gate attendant tried to make her pay a $150 fee to check the cooler.

"We were pretty mad. I immediately started crying," she said. "It was humiliating, they kept telling us it was because we were basic economy passengers; it really felt demeaning."

The couple ended up leaving their cooler behind. The airline later issued a statement in response to the incident, apologizing to Salow.

The customer should have been allowed to fly with the breast milk and we apologize that a mistake was made in this case. We have clarified our policies with our team members.