MrSaffron hits one of the nails firmly on the head when he says "thus ensuring equal treatment for all providers on a platform."
In order for every ISP to trust BT, Openreach has to meet stiff regulations on, effectively, being fair and equal. That fairness is implemented by the rules Openreach put in place, and by the ordering systems designed not only to implement the rules, but to prevent anyone from interfering "as a favour".
Great for fairness, and proving fairness. The downside is that, in cases like yours, where common sense says it is sensible to bend the rules, we find the rules unbendable.
So right now, your request is probably being treated the same as any order for a new connection, and sitting on a queue waiting for each step to be done - one of which is for a guy at the MDF to make the physical connection for broadband... We know it is already correct, but the standard system probably doesn't.
Openreach *do* have systems for odd cases to be expedited, but those systems have their own set of rules too. If your case doesn't quite match the rules, it can't be expedited, no matter how flexible you'd like them to be. I've also found that even when a case can be expedited, it doesn't make it much quicker.
You could ask your ISP to expedite, or at least find out if it is expeditable.
BT are, some 7 years on, still putting in place the separations that aim to keep Openreach at arms-length, as a way of appearing as an independent company. Its no real surprise that Openreach have much more to learn on this front.
They do learn things though - witness the shift from a company that "never deals with end users" (a common response to calls and emails) to putting in place an email helpdesk that will let you know what the plans are for SFBB for your phone line.