Good on you.
I don't like your chances of getting the letting fee back, but certainly give it a go - they misrepresented, and (I am not a Lawyer) surely you have some remedy under the CGA? I'd be interested to see how you go.
Be firm with their sales team - guaranteed they will try bringing people through outside of your agreed open home times. Stamp on it early, and tell them you are making the place available for them once a week, and stick to those times.
Good Luck.