Sorry to hear of your issues. It does not surprise me however. BT are a shambles!
I managed to score 0.00 on a speed test with their broadband and they insisted they weren't in breach of their contract. Unless you have infinity, they will (in my opinion) throttle your speeds and when you call to complain, blame the old copper wiring and then try to sell you infinity. When this happened with me, I explained Sky managed to use BTs own lines to provide a faster more stable connection, my speeds picked up that same day.
Hope you get a happy resolution.