1/4 turn mixer tap - ceramic washer

[Notts_1]

Hi,
I know it's a basic problem but I've looked through the past posts and can't see anything specific to my problem.
The tap in the attached pic is dripping. Easy, I think, I'll change the washer. There aren't any plates with screws so I find a grub screw on each tap and remove and expect the tap to come off and reveal a cartridge.
Problem is both taps don't move at all with the grub screw removed? I tried unscrewing in both directions, hammering, everything but they won't budge.
Are they cheapy taps where you need to buy a new tap assembly?

Any help much appreciated

thanks