When did you report the fault?
If its an external fault, then Openreach expect to fix it within three working days.
Then I would expect it to be repaired by the end of next Monday 11th, as working days do not include weekends, unless the line is registered with the free priority repair scheme.
It will be a phone fault, so provided you reported it as a phone fault, it should get tasked to Openreach to deal.
You can have a free divert of your incoming calls, to a mobile, or other UK number, for the duration of the fault.
I can only tell you, as just a BT customer myself, what is explained on this page.
You might get it fixed sooner, it depends on how busy Openreach are, and the nature of the fault.