To add to my post (above)
If a BT engineer should have to call at your home to check the BT line ask him/her how much it would cost to fit a NTE5 faceplate splitter (the NTE5 faceplate splitter has a centralised filter which is built into/behind the NTE5 faceplate) The job of the filter is to make sure that all devices sharing the BT phoneline with your ADSL service are prevented from interfering with your BB connection, & vice versa.
They can be expensive (if your lucky some BT Engineers with give you a huge discount) if not then at least you tried
its also worth asking as it does save having unsightly dangling microfilters hanging from your BT socket (it looks alot neater) & it helps prevent noise on your internal wiring interfering with your ADSL connection.