The postcodes given by codelook as the location of a cab are often seriously in error, or at least that is the case in central London where the area covered by each postcode is quite small. Is the new cab in use yet, or as in our case, a new all in one to serve a cluster of 75+ longish EO lines, is it listed but with a projected live date? For ours, WRVAUX54, it states "FTTC being Connected, live due by May 2016" Codelook also still lists the exchange bundle, Exchange 71, through which our lines are currently connected. How long it will be until we go live is anyone's guess as Lambeth are preventing BT from carrying out the last piece of required work.
Does the BR Wholesale Broadband Availability Checker
still list the old cab as being the one through which your phone is connected? Use your phone number not your post code when checking or if the number isn't recognised, use your full address. You want to see this change to the new cab before you will be able to order an FTTC based connection - assuming you cannot on the old cab.