Once they've got this sorted out...
...they might like to try to find out why emails sent by some users with TT accounts (including those with ISPs gobbled up by TT) sometimes never get to recipients with btinternet email addresses.
One of life's enduring mysteries... although on second thoughts perhaps it isn't. One friend of mine who is trying to resolve this runs into blanket denials of responsibility from both ISPs.
Snail mail might be slow but by and large it does get there.