DrC wrote:

Now I know that earth bonding does *not* mean earthing everything in
sight but does anyone have any idea what we have paid £77 for? I
suspect absolutely nothing!

As others have said it sounds like it, but nevertheless if there is
metal pipework within 3 m (horizontally) of the bath and/or shower tray
there should be local supplementary bonding between the earth terminal
of the shower unit and such pipework.

There should also be local supplementary bonding between the shower
earth and the earths of any other electrical circuits in the room
feeding equipment which is "within the zones". Usually this just means
you need a bond to the earth of the lighting circuit, since any fan and
shaver point will usually also be on the lighting circuit. However if
there is a wall mounted electric heater or towel rail in the zones, fed
from a ring circuit, that will also need its earth bonded to the shower
earth.

The zoned regions end horizontally at 3 m away from the nearest edge of
the bath and/or shower tray. Zones 1 and 2 end vertically at 3 m above
floor level; these cover the space above and within 600 mm sideways of
the bath and/or shower. Between 0.6 and 3 m of the bath/shower you're
in Zone 3 which stops 2.25 m above the floor.

HTH
--
Andy