I have a Nabis Aries Deck Mounted Bath Filler (a mixer tap!). It's leaking so I need to replace the ceramic cartridge(s). However I cannot remove the tap head. There is no grub screw, the hot and cold are just 2 mm painted on dots. There is a collar that can be unscrewed below the tap head but does not give access to removing anything without the tap head being removed first. I've had two plumbers look at it and they reckon it might just be a "pull off" job. Tried this with some force but nothing budged. As I have three pairs of these "type of nabis taps" I would just like to know how to remove the tap head. Simples - not! Anyone any idea - the original suppliers Wolseley UK Ltd don't have a clue! Thanks.
see below for pic of the tap: