There is no 20/2 (or is that the old 18/2 (now defunct for new customers)).
The line looks to be on 40/2, so "upto 38Mb" not "upto 76Mb". The 76Mb package cost £5 more, but you wouldn't benefit from it.
The downstream is suspicious with that rounded number, but every now and then a line will sync at a 999 figure by coincidence.
If it is banded, with an snrm of 5.7dB it doesn't look like you're missing out on much. If on a Huawei cabinet the line might have a few more Mb in it at 3dB.
Can you follow this guide and tell us which cabinet type you are on
http://www.kitz.co.uk/adsl/cabinet-lookup.htmalso if you resync the line is it exactly 19,999 every time?