Don’t know if you managed to resolve this issue, but if you want to see what speeds that BT thinks it can deliver to your home then try this URL to the BT Wholesale ADSL Checker:
BT Wholesale ADSL Checker
You will have to use the “Address Checker” not the “Telephone Number” checker, because that only works for BT customers, while the Address Checker gives an approximation of BT”s view of your available speed for both clean and impacted telephone lines. It gives you 2 ranges of available speeds for up and down.
If one of your neighbours has a BT line stick that in and you’ll get a view of the type of speed they can get, which, all things being equal, should be the same or similar to what you should be able to get.