Can't answer you problem, but imagine my surprise when after our BT line had been literally ploughed up by Farmer Giles, we were not getting any calls, nor could I access 1571 from my home office line. Calls out went fine, and I made a few lengthy calls to the US that evening.
Following day BT told me the pairs had all been muddled up on repairing them - so I'd mad about £10 of calls on my neighbour's line and bill.
Moral - dial 17070 after a repair by BT, and the auto-voice will tell you the line number.