ADSL problem: Really poor down speed but normal up

I have a problem with my F2S ADSL connection, I can see from my netgear router that the DownStream Connection Speed is 64kbps (normally expect 2000kbps) and the UpStream Connection Speed is 680kbps (which is normal). I contacted F2S support and I did the usual checks removed all other devices in the house, checked filters, tried the router in different sockets but it made no difference. They said they checked from the BT exchange to my house and that looked normal.

We have three sockets in the house I'm not sure which is the master socket because all have the same faceplate (none with front bottom half removable faceplate).
Nothing has changed in the house since the speed drop, they suggested I try a different router (I'm borrowing a friends to rule this out next), failing that they said I would need a BT engineer to visit the house to check the internal wiring which I would have to pay for.

Has anyone seen this before where the upload speed is normal but download has gone to pot?

Connection Speed: Downstream 64 kbps Upstream 672 kbps
Line Attenuation: Downstream 62.0 db Upstream 31.5 db
Noise Margin: Downstream 11.7 db Upstream 13.0 db

You'll need to find that master socket. It will be the one where the dopwire enters the premises and should be the only one with electronic components inside.

Let us see the results when you use the BT Performance Tester > BT PT

couldn't get the BT Performance Tester to work.

I did however find the BT main socket and with all other equipment in the house unplugged and using just a corded phone there is bad static and crackling on the line, I have a BT engineer coming out tomorrow to check for a fault. My ISP (f2s) suggested that this was causing higher than expected Line Attenuation hence to low downstream speed.

We shall see, if BT don't find anything it will cost me £127.

Although you here crackling on the line as it is, try the Quiet Line Test by dialling 17070 and selecting option 2 with the phone plugged into the test socket if there is one in your master socket.

During the QLT if you here noise when the phone is plugged into the test socket then it would suggest there is a fault outside of your property (as long as you know the phone itself is OK)