If you don't wait for the next available Eurostar they won't refund alternative travel, even if the issue is ongoing for days.
And yet my perception of Eurostar is that they were much more helpful when they have issues…
Some years ago, we had some (very) cheap tickets that came from an offer in a newspaper to travel anywhere on Eurostar, so I booked tickets to Brussels. On the day of travel, there was a bad rail crash in Brussels, and all trains were suspended indefinitely. Eurostar offered to let us go anywhere else (at no cost to us), give me the cash back or give me a voucher for future travel. We chose to travel to Paris instead, but unfortunately the carriage we were sat in had failed aircon. The on board staff were incredibly apologetic, did their best to move people to other carriages. for those of us who they couldn’t find room for, they left trolleys full of bottled water at each end of the coach, and stamped our tickets so we could go to the office at the other end of the journey to claim a free return ticket.
Compare and contrast that with the last Avanti I travelled on:
Me: “sorry, I know you’re doing ticket inspection, but this coach is very hot - is the aircon on?”
TM: “it’s broken, what do you want me to do about it?”
Me: “any chance of some bottled water for the passengers?”
Tm: “you can buy water in the shop”
Off topic, are the pendolinos join a bit rubbish after their refurb? It’s a rare treat when you get one where the sockets work, and it’s 50/50 if it’s got working aircon, or am I just unlucky?