Your current sync speed of just 1Mbps (as per a GEA I've just performed) is above the Minimum Guaranteed Speed of 0.4Mbps and within the circuit Estimates our Supplier has provided for the line. Having said this, there is a chance you could squeeze a bit more out of the line, so I've just tried to set your SNR to 3db, but the request has auto rejected 3 times. I'll have a chat with a colleague and see if we can work out why this is.
In the interim, can you set your connection into the Test Socket and see if the sync rate improves? How to do this can be found here.