Using a Dunne & Bradstreet Search engine I have obtained personal email addresses for CEO/nPower, and have drafted an email along the lines of
@Roadster280 's suggestion. I have also given a colleague who is flying back to London tomorrow a letter and she will send it recorded delivery.
I have also emailed my MP; asking a few neighbours and friends in the Lakes, it seems they have been plagued with these egregious letters and sundry crap service from nPower, I did speak to Trading Standards today but it's not really their bag, and they suggest I go to the regulator, after all internal processes are exhausted. What annoys me is that we are obliged to accept poor service (which we pay for) yet in most of our professional careers, we could be sacked if we behaved in a similar way. I ahve to say that United Utilities aren't much better.
And thanks for the comedy input; the media would portray me as 'our Man in Wherethef%ckistan" and then quote a Zoopla value for our house, then adding photos of me pi$$ed at the Embassy QBP. Google street view shows it with scaffolding; not the best view! And I flew, in the dim distant past, on 'Submarine Aircraft'