I'm Swiss. My unconditional offer from Bristol states I am to pay overseas fees?

I have been given an unconditional offer, but they have stated that this offer is given on the basis that I will be paying the much more expensive 'overseas' tuition fees. When I applied to UK universities I was of the understanding that Switzerland would be treated as a part of the EU in terms of paying fees and thus I would pay the 'home' tuition fee rate. Have they made a mistake or have I? Thanks for your help