Have you contacted BT yet and asked they send out an Openreach Engineer?
They were due to send an external engineer this morning but there has been no sign of anyone or any change in speed etc, just an alert to say the issue has been fixed! I will see how it goes over the next 24hrs.
Internet has dropped 4 times today so far! And speed 30MB below what we are paying for. I called BT again and explained the issue and said I thought it was a network issue and we may need to be shifted on to a different connection. We have another engineer coming out on Friday. Fingers crossed they fix it this time!