He's got close links with BT Wholesale and has successfully managed to get a lot of stuff done. He got the BT database changed for me two years when it said I couldn't get 2Mb, when it was obvious that I could.
Just email him the copy of all your line stats and explain that your SNR has jumped up to this ridiculous figure because of a line fault that has now been rectified, and that you have been told that he might be able to help, so please would he see if he could do something about getting the SNR reduced back down to 6 or 9dB for you.
Tiscali should be able to do this, but given it often involves a lot of to-and-froing with the ISP <--> BT, they probably just can't be bothered. That reply you received from Tiscali was absolute nonsense, the 'support' person obviously didn't even understand your question.