Neither are with BT, but I presume they will allow you to have two lines with different packages, though if a business they insist on business rates.

Meh, just being pessimistic - I got that sort of estimate originally. After some fiddling over the years I now get 1800ish sync, 1500kbps profile.

Deffo order on the original line, get a decent router (2wire 2700 for example), isolate everything except the master socket, spend £10 on an Openreach filtered faceplate, and see what it can do.

Seems reminiscent of my dealings with BT when trying to get a phone line into our new build.

here

3 months and SEVEN separate and concurrent order numbers later we had a phone line, only for it to be disconnected after 3 days when the BT adminoids then deleted all the order numbers (including the one linked to our working phone line) and then tried to bill us for an early disconnection charge.

The contacts in the above link were very, very efficient and could make the seemingly impossible, possible (having an engineer out at 6pm on a Sunday!).