So, an update.. I got sidetracked a bit with following this up, life issues..
So yeah.. Zen contacted BT, who came back with the standard copy paste reply, "You're in a plan to get Superfast fibre but we haven't started work yet" and said there was nothing else they could do.
I am under the Fastershire scheme, and their exchange info page says all work has been completed in my area. I've checked a few numbers for my neighbours, and they can all get FTTC. I've sent off an email to the fastershire guys and am awaiting a reply.
The new cabinet is literally 50ft away from my front door, and all the houses in this row were built at the same time, and were previous EO lines. So if my neighbours were all switched over to the new cab, why wasn't I? Something has gone wrong somewhere.
Can anyone on here give BT a prod, and see what's wrong?