BT are an incompetent bunch of buffoons that make Talktalk look professional..
Actually, in my short and inglorious stint as a Network manager I found that BT, in most cases, were the least-worst of the big telcos to deal with. Mostly because the majority of the engineers had a Clue(tm). It was their back-office processes and management that seemed to have the most ability to completely muck things up..
 Mind you, this was about 10 years ago so most of those engineers have probably been sacked, made redundant or quit in disgust.