All you can do is to raise a fault report.
Its possible that the line tests fine from the exchange end, because its connected to the wrong house.
Honestly.......they sometimes connect it to the wrong house?
Are they qualified to do the work?
It Openreach that do the work, and sometimes its sub contracted out.
Most errors are caused by inaccurate cable pair records, where someone in the past has changed a pair over, and not updated the database.
If they were changing a pole, then every connection would have needed to be disconnected.
When it came to re-connection, they would rely on whatever is held on the database, right or wrong.
Perhaps in your case, in the past, you had a faulty cable pair and it was changed out but not recorded.
When they came to reconnect all the pairs again, yours would be reconnected to the old faulty pair.
The good (new) pair, would have been connected somewhere else.
They will have to come and sort it out.