If experiences like mine are anything to go by, the person on the other end of the phone knows bugger all. Give them an address, an MPAN and ask to know about the connection, earthing arrNgment, supply characteristics etc and you're met with bloody silence, like you're just spoken to them in Klingon"never forthcoming" dont know what means, the DNO will always be avail for advice for distribution matters.
But what would I know?