As there was no noise on the line and that you only have one phone socket (The LJU Master Socket) then unfortunately this maybe the max speed your able to achieve.
As already said your line has a line attenuation of 59.7dB your landline is approx 4.3km long from your property to your local exchange. In Ideal conditions I would have estimated a speed between 2mb to 2.6mb on AdslMax (G.992.1) for a good quality line. Your current sync rate is not far off the 2mb mark, this could be down to many factors such as line material.
As Keith has said you maybe able to opt out of the BT Vision service, however your contract will still stand unless your broadband service doesn't work at all.