MY SEAT WAS CHANGED!!!

Hi so I'm heading to Paris in a few weeks. I will be getting there via Eurostar. And I change my seat to be more towards the front of the train and now they've changed me to the very last cabin. I wanted to be by the luggage things because I'm so nervous about my stuff being stolen and everything is totally changed now. I might just give up and pay the money to upgrade I don't know what to do.