Premium Unlimited Plan, no cell service in UK

As the title states, my daughter is in London (now on the train to Scotland) and she has not had cell service since she arrived on December 22. I've talked to 5 different Xfinity reps (including tech support and supervisors) but no one has been able to fix this issue. She has a new iPhone 17 pro that was working fine in the US before she left. Her eSim is activated (she sees no bars, but it doesn't say SOS either), airplane mode is off, roaming is turned on, but still no service (and no options when she chooses cellular in the setting menu). She is able to use wifi but we are paying for global service and she doesn't have it. What else can we try? We're both at our wit's end.