I had the same problem this evening.
Pages taking ages to load, (4 - 5 mins to get the log in screen!) the log in screen then just returning server error messages.
I called the help line, got a BT message stating the network was congested.
Several calls later I got an engaged tone - BT suggested ring back, pressed 5, got told ring back was not avalaible on that number.
I finally got through on the international help number, 10 mins on the phone, being toild to clear the cache and wait 10 mins before rebooting (They finally admitted 1 second or 10 mins would make no diffference.) Said I wanted to complain, and register the fact in case I got fined and repeated this until I was put though to a 3rd person. who gave me a case number and took my tax reference number so that if I could not file and got fined I could appeal.
Looking at the new guidelines on their site I could not see why I have a tax form anyway...
...what's the legal position on billing the inland revenue for my time completing thier form when thier guidelines suggest I don't need to have a form anyway?