thanks for the replies so far.

I tried pulling the knob off earlier when I got home from work but it
didn't seem to want to budge. Even tried levering it off carefully but
it just seemed to spring back into position.

I'm guessing Aqualisa isn't open on Saturdays.

The local Plumbase have told me they have the grey cartridges in stock
for £78. I think that included VAT but I could be wrong. It needs to
be fixed asap as the water supply has been shut off at the main stop
cock.



bill