Two Customer Service Agents Lied to Me

There is no proof he was misinformed. Did you or him even due your own research to see what countries are covered? There would have also been notifications sent advising you of the international charges. Were they ignored? 

So the customer service agent confirmed that when I listed the countries another agent said they were covered and he was good to go. One was covered last year when he went and not this year. He did receive a notification, but it was while he was still in a covered country, which is why I contacted customer service about the alert. I gave 2 CS agents the list of places he was visiting. Neither said one was not covered. One even "reset" the day pass because they said it should have been working and he should not have gotten the alerts. Both confirmed he was good with the day pass for his itinerary. A third agent confirmed I was misinformed, but also told me one country he visited was not covered, when it in fact was. (that was after he had returned) He continued to get the notifications even when he had returned to the US for two weeks. Overall, lots of bad info from CS agents who do not seem to have the correct information to provide to customers. Had I been told when asked he was not covered, or that there was a chance a country previously covered no longer was, he would have amended his cell usage. But we were told he was covered by the day pass. 

What country(s) are we talking about?

He travelled to Guam, The Northern Marianas, and Palau. All were covered last year. They apparently dropped Palau, but he started getting notifications about usage while covered by the day pass in the Marianas. 

You can file a BBB complaint, which will get you escalated to the Office of the President. They have more power to make adjustments even if the billing is "technically correct."

Did you or husband check the list on the date of travel?  

Just because it's not listed now, doesn't mean it wasn't listed at the time he/you asked at&t.

   It's important to check the list because many countries are not covered.

https://www.att.com/international/day-pass/?source=EC1N250000000000P&tfn=homesolutions&WT.srch=1&wtExtndSource=%2Batt+%2Binternational+%2Bday+%2Bpass&ds_eid=700000001881312&ds_cid=71700000085439208&ds_agid=58700007246258172&ds_kids=p65009738633&gclsrc=aw.ds&gad_source=1&gclid=Cj0KCQjwxeyxBhC7ARIsAC7dS3-Lu2Mq5q4_C8ilqK573Y44W7Y3XdXZlfdu1UjBNqp_vOuWuVksrgYaAo-MEALw_wcB&gclsrc=aw.ds#p

It was literally while he was in an airplane traveling to the location. So, not sure how much closer to travel it could have been.