Surprise, Surprise - Despite assurance from support that their servers were ok I find today that I can login just fine!
The odd thing is this: On the day of the problem I was able to login from home but not from work. This suggests it was a network routing issues or content server problem for traffic leaving the TT(talktalk) network since the CSA (customer services advisor) could access the details fine. I could do it on my BB (broadband) connection but not from work - confirmed at the same time via VPN and Remote desktop that evening that I could not connect from work and could from home.
The clues to the issue were in the Sun Java console - at work the Java console was throwing up a ton of errors saying things were missing (same Java version and Firefox version at home and at work). This suggests to me that one or more TT's content servers was available internally to TT but was not visible to external connections on their network. But at least they earned another £1.50 or so for this 'free' service.
Thank God I was too busy yesterday to call them again. Uncanny how my 3 day prediction below came true about it - Woot!