An installation we've done recently has the electricity meter spinning backwards. Do we notify the DNO of this or the electricity supply company? Is there a special form to notify them of this? (and please don't reply saying 'don't bother' !)
we always notify the DNO via, the notes section on the appendix 3 form, and they put a section on their reply saying they've passed this information on to the supplier.
Many fit forms also have a section asking about this, and I'd recommend telling the customer to notify their supplier, but I'd defo note it on the appendix 3 form, then at least you've let someone official know about it.