A comparison point :-
BT Recorded Line Length to Exchange (m): 4123
This is a 21CN line.
The current Downstream BRAS rate is: 3.78 Mbps (6 dB SNR, 54 dB attn)
The current Upstream BRAS rate is: 0.45 Mbps
Previously the BT number checker picked up data for your active service and fed it back as available speed, this doesn't seem to be the case currently as I have a line saying "up to 3M" that syncs at 8128. Sounds like you have a database glitch the other way.
Sounds reasonable. If this is the case then BT OpenReach are likely to charge for coming out
Ed to add: I guess what I'm saying is that there isn't a shorter route, the ISP might be making it up and the TPON overlay will be long back to the exchange and that won't be changed by the reconnection work unless you're on an exchange boundary and they're connecting to the "other" exchange (Hampton in Peterborough for example is fed from two exchanges) but this seems unlikely TBH.
BT are saying that i'm connected to cabinet 49T, I'm assuming that the T means TPON, as I said before the cabinet is not in use, well if I believe the OpenReach engineer.
Don't think that my ISP (Merula) is making it up, they're just reasoning why the adsl checker would be quoting the higher figure.
I'm pretty sure, I'm not on a exchange boundary.