it was a lift and shift at the fibre cabinet to resolve a dead port on a line card is how I would describe it.
Yes, 'cept that during the lift and shift, the new port is allocated and proved by the 'help desk' so
So long as the engineer reported what he did and gave control the correct port, then the remote people will then reconfigure the mapping of the port to connect you to the correct provider.
Seems incorrect. The port should be live and have been demonstrated as working by the engineer before he left site.
It's either the wrong port, or more likely the new port has been incorrectly built for the OP's circuit. Also there is intermittent issues where in some areas (Godalming being the one I know of) the software that builds the new port doesn't work correctly, and the new one won't make PPP. The last option is that what ever was wrong with the original port has just been copied and pasted on to the new one.
To the OP, just a thought, EE haven't sent you a new router to try during all this have they ?