BT are now sending an engineer (but not until TUESDAY !!!) but I really don't think it's a line issue...
The engineers can be be sent out for other kinds of visits. LLU SFI, or more likely, as you are with BT BB, a broadband boost task.
You have sync but no PPP. Easiest option, your line has been noused up in the exchange, and you are now on the wrong port.
More likely, 21cn Fujitsu exchange equipment has has gone tits up. Ensure that the engineer who turns up has their JDSU or Exfo configured to test PPP, if not they should be ringing the 'coaches line' and asking how this is done. This way they will have something to bat with.