Hi and welcome
63dB indicates a long line. The 4000m could be "straight line" rather than length of the actual phone line.
You can check the "crow flies distance" from here. Put in your phone no and post code - then once the results come up click the locality button.
http://www.samknows.com/broadband/checker2.php>> IP profile was 1000k,448kbps upstream and 1856 kbps downstream
That sounds about right
>> my upstream is still 448kbps but my downstream is now 968kbps.
There appears to have been some sort of deterioration on the line
Re flooding - It is a possibility water on underground cables can cause problems.
>> he was told yes my line is set at 500k but he would lift this to 2mb.
If your line is syncing at 968 kbps then the line will indeed be set at 500k - its the way the dynamic system works. Even if he did manage to get someone to reset the bRAS profile, then as soon as your next sync occurred at below 1152 kbps, then the DLM system would automatically switch you back to 500k.
The fact that your router has never synced above 2272 kbps on MAX even temporarily (and the 63db atten) would indicate that your line isn't capable of a fixed 2Mb service. Your line could probably cope with a fixed 1Mb connection - where at least you would get the full 1Mb rather than messing with bRAS and IP profiles.
Its certainly an option to consider.
Alternatively at the end of this month some new IP profiles are going to be introduced which may help you.
The new profiles 750Kbps and 1250Kbps may be the ones that interest you.
If you can fine tune your line and stay there then you may pick up one of the higher profiles.
Currently your SNR Margin stands at 13.9 dB - which gives you a bit of leeway. Its worth giving your router a reboot NOW whilst there is a good margin on the line and see if you can attain a higher sync speed.
Immediately after you have re-synced, can you make a note again of your line stats again.. I'd like to see the SNR Margin straight after a reboot to try see what Target SNR has been set on your line.