TBH , you haven't really established that it's not the phone itself that's at fault, and so , should you find a way to report the 'fault' , you would be taking a chance asking for an engineer visit.
if you don't have another known working phone to try ( and you can buy a corded landline phone for not much more than £5) , you could borrow a friend/neighbour or relatives phone to try in your master socket test port , or take your unproven phone to someone else's home and try it in their phoneline.
As already said, you can report a problem in many ways, even if your phone isn't working, and given that you can get on line, you could even report a fault via the BT website
