No network ABROAD - "phone not allowed"

I live in the EU. All the home country carriers and carrier plans work in any EU country. Like I said in the post, my first trip abroad I used my carrier data as if I were home. That's the law in all EU countries. By all means it should be as if I didn't leave the country at all. The problem only arose when I switched to a new carrier, but only for EU countries. Like I said, when I'm near the border of a non-EU country (briefly, on a specific train line), my phone automatically switches to the foreign network and works fine.

But you have to have data roaming on to use data abroad? The bills are not the issue (I only got a huge bill one time / first time, I should have specified) but in the EU I should be able to use my own carrier plan. The issue now is that 3 times in 3 different EU countries I couldn't use the data, and this last time I had no service at all. When I'm on this specific train, I turn off data roaming but my phone still switches to the foreign (non-EU) network. It's like I have a restriction for EU countries only, except they told me there are no restrictions for my plan or my SIM card.

Like I said, first time abroad with the phone I was on a different carrier and it worked fine. The second, third, and fourth time I was abroad with this phone (all different countries), I was on this new carrier and my phone was a useless brick. Or well, the photos are great.

Thanks. I also plan on trying to get them to lower the bill since I couldn't use the SIM for 4 days.

I should add that I did speak with someone on the phone, they said they'd restart my SIM card, whatever that means, and that it should work now since everything's fine on their end, but I still had no service. But I might try again.

I did.

I mean it has to be, otherwise I'd have problems all the time, but they're being useless, saying everything's fine on their end. I'm going to have to confront them in person (again).