I think this, ‘Specialist Engineer’ to create a New Port in the PCP thing is nonsense, given you have NDT.
I’m pretty sure what the issue is, is there is no more capacity in the D-Side Network in a section of cable length somewhere between the PCP and DP. As in a 20 pair cable that has 20 working circuits on it and you’re number 21.
That being the case it would need a relief cable. Depending on the length of the cable needed, where it needs to go, i.e. along a busy 60mph road, etc is how long it would take to pull in.
If I was you I’d contact BT and demand they contact Openreach on your behalf, which is their Responsibility as your Service Provider and get a real in layman’s terms answer on what exactly the problem is, what needs to be done to rectify it and when they plan on doing it.