These are the current statistics from my HomeHub5 on Infinity 2.

6. Data rate: 2696 / 18000
7. Maximum data rate: 3295 / 30699
8. Noise margin: 6.5 / 16.9
9. Line attenuation: 31.0 / 29.0
10. Signal attenuation: 30.4 / 25.4
11. Data sent/received: 246.5 MB / 5.3 GB

Are these bad or very bad. I am on Infinity 2 but am paying less than Infinity 1 because of the poor speed that I complained about.

Is there anything I can do to improve my connection?

Are 9 and 10 particularly bad?

Can I ask to be connected to my nearest infinity cabinet rather than the one which I am connected to? This is a great deal further away from my home. There's still vastly more copper in my connection than fibre.

Using BT's ADSL checker my cabinet has
FTTC Range A (Clean)
25 High - 17.5 Low Downstream Line Rate
5 High - 3.2 Low Upstream Line Rate

FTTC Range B (Impacted)
20.1 High - 9.8 Low Downstream Line Rate
4.2 High - 1.2 Low Upstream Line Rate

BT's broadband checker constantly shows my speed as
17Mb Download and 2.45 Mb upload.

The ADSL checker shows that both FTTC Range A and B are available so why am I on the impacted range although the un-impacted range would only offer a slight improvement on bad figures?

Are any of these figures likely to improve in the foreseeable future?

Looks like your not getting the full speed as these mine here
Are you plugged directly to your master socket?
If these do not change might be better downgrading to infinity 1.

These are mine on BT Infinity 1

1. Product name: BT Home Hub
2. Serial number: +068543+NQ51212305
3. Firmware version: Software version 4.7.5.1.83.8.204.1.11 (Type A) Last updated 09/07/15
4. Board version: BT Hub 5A
5. DSL uptime: 4 days, 09:23:35
6. Data rate: 9999 / 39952
7. Maximum data rate: 28303 / 91029
8. Noise margin: 22.8 / 21.1
9. Line attenuation: 17.3 / 15.7
10. Signal attenuation: 17.7 / 15.7
11. Data sent/received: 12.9 GB / 75.3 GB
12. Broadband username: bthomehub@btbroadband.com
13. BT Wi-fi: Yes
14. 2.4 GHz Wireless network/SSID: BTHub5-SRKJ
15. 2.4 GHz Wireless connections: Enabled (802.11 b/g/n (up to 300 Mb/s))
16. 2.4 GHz Wireless security: WPA2
17. 2.4 GHz Wireless channel: 3
18. 5 GHz Wireless network/SSID: BTHub5-SRKJ
19. 5 GHz Wireless connections: Enabled (802.11 a/n/ac (up to 1300 Mb/s))
20. 5 GHz Wireless security: WPA2
21. 5 GHz Wireless channel: Automatic (Smart Wireless)
22. Firewall: Default
23. MAC Address: 00:37:b7:1c:8a:54
24. Modulation: G.993.2 Annex B
25. Software variant: AA
26. Boot loader: 1.0.0

You're certainly within the quoted range anyway, although at the lower end of it.

The downstream noise margin is too high, and is a result of DLM taking action. This could be as the result of a poorly performing line. Any kind of line fault or poor internal wiring could have caused this.

Under perfect conditions though, you can't expect to get any more than 30Mbps, and this is going to be down to distance from the cabinet. There is no way to get changed to another cabinet.

fmradiotuner1's stats are irrelevant as they are obviously much closer to their cabinet.

Reboot it, you're considerably under what your line can do.