Sync Speed Problems

I had a new phone line from the pole put in at the start of June as it had died (most likely when the house was rendered) and I had a constant sync of 16380kbps (it's the top on 16mbps anyway) but for about the last 2 weeks the sync has been dropping and for the connection to hold steady I have to had to force it to connect around 12000kbps. I'm pretty sure this happened before I connected a new extension on the internal wiring but I haven't had chance to test that yet. Just seeing what ideas people have for what maybe happening, I live about a mile away from the exchange, would get a constant connection at 16mbps with about 26db att and 8 snr but now it is about 7-10 snr on the 12mbps sync. Will try taking the face plate off tonight and go straight into the test socket but i can't really see this making a difference. Any thoughts on this would be nice and i'll report back later with my findings from the test socket

Holding comment until faceplate tests are done

thanks for the reply, just checked and i accidently put a wire from the extension into the adsl side of things, sync speed is perfect again, strange that it was still connecting but wouldn't stay stable above 12000kbps

ADSL Link Downstream Upstream
Connection Speed 16380 kbps 764 kbps
Line Attenuation 26.0 db 14.4 db
Noise Margin 8.3 db 11.0 db

sorry for any time wasted and you can now close this topic