The broadband and phone service I had from the Post Office on my market 1 exchange was flawless. My only problems were the bills they sent to the wrong address all year (I assumed I was paperless until they dropped them all round) and the fact I left during the Talk Talk and customer service switch over which caused a great deal of confusion.
In short, the service they provide is good, the way they organise themselves is poor. This can work to your advantage though, I was meant to pay £60 for the phone line to be installed... never got charged!
Virgin Media 60mb