Well my problem is fixed at least
I waited with baited breath for the jeopody teams analysis of the problem, but after doing the usual [censored] (pull everything out etc) they stunned me by announcing there was nothing wrong.
A few hours late everything suddenly worked as normal again after the phoneline went dead for the umpteenth time, and everyone I knew who had TT on my exchange had normal internet again.
I asked TT what miracle occured, but they didnt know either.
So to sum up
Internet goes bad for no reason, and comes back for no reason 3 months later. TT has no idea why this happened and people still defend them when it's clear they have no idea how their own network operates.
Really?