Oh, it almost certainly isn't because you are too far from the cabinet, and almost certainly going to be because of a data problem.
Getting data changed seems to have long been an issue with the setup of Openreach - where they won't talk to you, only an ISP. Yet ISPs aren't very willing to take on support cases like this.
My own issue (of a slightly different nature) took 3 months to resolve, even though the engineers who attended could see the problem instantly. The first month was getting someone at the ISP to take ownership, while the rest was getting Openreach to do their side of things.
Is your cabinet one that has been in place a long time, and has only recently had an FTTC twin added? Or is it one when BT have recently placed the copper cabinet too? The latter cases seem to come with an increased share of drama.