I am trying to top up the oil on my MK2 1.8 Zetec Mondeo and I cannot get the poxy cap off!

It says on the cap "click" "click" with arrows pointing the way to turn. After this not working the handbook states twist and pull but I cannot get the thing off!!

Iam feeling like a bit of a tit at the moment but can anybody suggest anything?

Cheers all