I was over charged at the cinema who lied to me and were rude what should i do?

So my local cinema has a big sign saying all tickets before 2pm (mon-thurs) �5. so on wednesday i went to the cinema and got a ticket for a film starting at 1:45 (or at least thats what it says everywhere you look, i.e. the internet, teletext, their phone number, their timetable, you get the picture) we all know that when they say 1:45 the film doesn't start till at least 2, but nonetheless the advertised time was 1:45. therefore I should have been charged �5. but i was charged full price �6.50. when i kicked up a fuss they kept saying that the actual film doesn't start till 2 o'clock so pay the full price. in which case does that mean that trailers dont count? are they free as you are only paying to see the movie that doesn't start till 2? or was somebody trying to pull a fast one? I have been a couple of times before when a film was advertised to start at 1:45 and always got in for �5. anyway, this really annoyed me, as i feel they have wronged me, and they were rude about it when i asked why i was paying more than I should. is there anything i can do? go and watch some free trailors? boycott? ask for my money back again? what would you do?