I’m going to sue xfinity mobile

I bought iPhone 14 Pro with subsidy at 2022 and paid off 3 months ago. They sent email saying my phone was unlocked based on their policy. 
last week I tried to add foreign eSIM for my travel but it failed because my phone was locked. I contacted chat agent multiple times. They all said that they would unlock it in a few hours but it never happened. I called support and the agent said that she escalated the ticket and it would be unlocked next day. 2 days later, I got an email saying that they wouldn’t unlock it because it didn’t meet requirements. 
Now I’m I Japan and my travel is severely degraded because I can’t use my phone with internet. They locked my phone illegally and I think I should sue them.

ls there anyone has similar experience? I’m wondering if I hire lawyer or I can go with small claims by myself.