Don't be too trusting with the company called National Numbers if my experience is anything to go by, especially their proclaimed "Price Promise" to beat any other dealer.
I ordered a number from them late one night, giving VISA details for payment when their office opened next morning. Within an hour I found the same number with another dealer for £65 less, so I sent another email the very same night (a Sunday night) asking them to adjust price in line with their Price Promise when they processed the payment in the morning.
What they did the next day was ignore my second email, process a payment at the higher price and then claim they would not match the price because the number was no longer available from that dealer (of course not - they'd hastily 'sold it' to me by now!!) and nor would they allow a Price Promise retrospectively.
So it would appear the lesson here is if you see a number cheaper elsewhere, buy it elsewhere, there's no point and absolutely nothing to gain in going back to National Numbers for something that's cheaper elsewhere. It is clear they will evade honouring that promise whatever it takes.
A price promise honoured would have cost NationalNumbers a slight loss of profit (the number itself cost them no more and no less to buy whatever it is sold for), and would have spoken eloquently of the company's trading ethics. The behaviour they have exhibited - grab the money and hold on to every penny at all costs - in my opinion, reveals a company that only gives any semblance about customer care until is has the money, and once they have your money they don't give a hoot. Good companies stand out, not by how many 'satisfied' customers they can boast (that could just mean none of that number has actually complained); but how it deals with really resolving problems for unhappy customers.