ADSL fault is unfixable

I have been trying to get my ADSL line fixed correctly for more than 6 months. <br> At the last attempt to fix it, the broken connection was restored.<br> -A day later the signal to noise margin on the 10 Mbs download dropped to below 6dB<br> -This caused the connection to become unstable<br> -The signal to noise margin on the upload side is 12 dB. this is absolutely OK.<br> -The line attenuation on the upload is 15.5 dB also excellent.<br> -The line attenuation on the download is 29.0 dB this matches the HIGH signal to noise margin indicated. <br> -There is audible NOISE on the analog phone line- this would also explain the high signal to noise margin on the ADSAL line (same pair of copper wires) <br> Seeing as these diagnostics are run on the same pair of copper wires, it should be easy to determine that the fault is only affecting a part of the digital signal, therefore, the fault probably originates at the exchange.<br> I AM SICK TO DEATH OF EXPLAINING THIS!!!!