Any plumbers? Please help with this tap!

[MooMa83]

We have a dripping tap and are trying to access the cartridge to change the washers. However we can't get the blasted casing off. The screw at the end isn't budging. Do we need a different screw, or are we being really thick and should be doing something differently?!

They can get really seized up.
Have you tried hitting a hammer on the end of your screwdriver? That sometimes works.
You can also get a WD40 spay that's pretty good at loosening stuck screws. You apply and leave for 30? minutes.
I've seen advice about heating the screw up as bell but haven't had much luck with that myself

If all else fails drill it out. Seriously try the other ways first it's a pita.