Well indeed, i think if she hadn't sounded so confident and convinced it was wrong i wouldn't be so confident.I would bet on the Website being correct just if I am being cynical
However, give this a read;
http://community.ee.co.uk/t5/Apple-iOS-Forum/iPhone-6S-with-a-sim-only-contract/td-p/350900
Seems a chap got one and tried a different sim and was fine. Make sure you read down the thread though.