just tried yet again to get thru to query an inflated last bill-estimated! altho we had a smart meter installed by them! creepy voice says wait right there - clicking noises then phone dead. This is why we moved to Octopus, NP famous dreadful service with rude abrupt automaton like call handlers.
Beware the smart meter folks! Which? put NP next to bottom of 30 firms. Worst firm ever, do some research, avoid avoid avoid.