It's already 21CN but is due for FTTC
That kills that idea then, unless you are to be moved from an old 20CN DSLAM to a 21CN MSAN.
As for them checking their and the Wholesale systems, ummmm. As in:-
"BT say there are no orders in any of the systems, they checked the BTW systems too"
is incompatible with where we started - your earlier
"it (the BT Wholesale checker) also told me that there is a Broadband cease on the line which is due to complete on 23 December".
Though that could be reading the line status from an Openreach database and your level of contact doesn't have access to that.
All you can do is keep on at them to find out what is going on, or just hope and pray that my suggestion at the start of this post is right. Not good

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