As you've been implying, all this talk about fraud may well be inappropriate - as you've said, it depends entirely on what has been said. All TTC told us what that, in the course of doing a CU change, BG 'insted on' installing supplementary bonding, at the customer's cost.Incidentally, if the person doing (or specifying) the work was unaware that the regs have changed and supplementary bonding is no longer required (subject to ...) then it actually wouldn't be fraud. ...
For a start, although it's unlikely not to be the case, given that a 'double RCD' CU was being fitted, we don't even know for certain that all of the requirements for omission of supplementary of the bathroom were satisfied.
However, more to the point, 'insisting' on installing the supplementary bonding does not necessarily constitute fraud. They could have tried 'insisting' on painting all the cables red, white and blue, or fitting a gold plated CU, but the customer presumably could have told them what to do with their 'insistance'. I would have thought that it would only be fraud if they had given the customer reason to believe that the extra work was 'required' (e.g. by law or regulations) when this was not true.
Returning to the OP (rather than the case TTC mentioned), it sounds as if BG did not even offer to (let alone 'solicit') the extra work which they felt needed doing - in which case that clearly could not be fraud and, I would have thought, was far more likley to be a case of CYA (even if misguided and incomplete) on the part of the (seemingly incompetent) individuals concerned.
Kind Regards, John