Re:slow Talk Talk
Looking at your numbers, they break down as:
Approx. distance form exchange: 3.7Km
Expected max speed: 4.839 Mbps
Attainable downstream rate: 4.536 Mbps
Attainable upstream rate: 1.047 Mbps (typically the max for ADSL2+ without Annex M support once the ISP has added a little margin for stability)
These numbers remain fairly consistent throughout the screen shots.
Next we have SNR which varies between 21dB (best case speeds) and 25dB (worst case speeds). I'm unsure why Talk Talk are trying to run with such high SNR, as although it will be very stable, it's giving up almost all of your speed (given your distance from the exchange) in the process. Typically you would see this between 3-9 dB.
My recommendation would be:
a) connect your DSL modem directly to the master socket to take any strange, local issues out of the picture (i.e. probably a cabling issue within the house, but can also be caused by a faulty phone or a security alarm) and see if it alters the attenuation. This will identify if you really are ~3.7Km's from the exchange
b) with the DSL modem connected to the master socket, ask Talk Talk to get 2nd line to look at the issue in case yo have been placed on the wrong profile. I have seen this with Talk Talk before and it takes around a week to get to the right team who can fix the issue.
c) I have no experience with the Netgear DSL router you are using but it may be worth trying another unit if you have one. Given the numbers shown, it maybe a router issue stopping the DSLAM in the exchange training correctly.
I would expect you to be getting 3Mbps+ downstream and 1Mbps upstream - not great, but a step up from what you have...