Main earth bonding

[JohnW2]

Ask them if they charge for this unnecessary work.

And ask them if they have done a risk assessment associated with making isolated metal pipes part of the electrical installation.

Quite so - although, as I've been saying, if they know anything (I'm not convinced!) they will have a good answer to that, since the 'isolated' metal pipes will, in fact, almost always already be earthed (and hence 'part of the electrical installation') via CPCs. ... and, of course, I've already suggested:

If it were me, I would be inclined to ask them what (if they have a clue!) is their understanding of the purpose of Main (Protective or Equipotential) Bonding!

Kind Regards, John