I helped a friend to sign up on Tuesday. He is connected to Malvern exchange (WMMAL) which according to samknows has 6 suppliers and is thus a market 3 exchange.
On trying to sign-up it gave us the market 1/2 price, so called up. Sales said that there was nothing he could do, he could only go by what his system said, so put us through to technical support.
Very helpful chap, checked samknows and agreed that it is a Market 3 exchange, and that Plusnet internal lists were out of date and were in the process of being updated. He told us to sign up then raise a ticket and he would be put on the lower charging.
That is what we did. However the response from the ticket was to the effect "We agree that it appears to be a Market 3 exchange, but ofcom has not listed it as such. You will have to take it up with Ofcom" (It has only been read to me over the phone, so it is not word perfect, but the meaning is correct)
Now according to the Ofcom link at the bottom of this plusnet low cost area page
Ofcom has a definition of Market 3 not a list.
We know another Plusnet user on this exchange who is paying the lower cost.
How should we proceed? He does not want to continue if he will not get the lower cost, I guess he has 7 days (until Tuesday) to cancel.