I can't get the further diagnostics to work, Ive tried it loads of times already tonight using different computers too.
I do have a home hub 5, but can't see how to get any results off it yet.
Thanks for all of the help so far everyone.
To get the stats from the Homehub you go to troubleshooting > helpdesk
Your estimated speeds are between 11.5Mbps and 29.3 Mbps so going by the speeds you have posted you are at the higher end of your estimate so I doubt there is anything wrong with your connection.
Because of the distance from the cabinet that will be the cause of your relativly low speeds and it would be worth downgrading to Infinity 1. It won't lower your speeds any more than you already have.
See graph for distance to speed. Infinity is VDSL2
Here you go, I didn't even know how to snippit until a few minutes ago!
It looks like there could be a problem with your line. Your noise margin is higher than the optimum of 6 and the data rate looks like it has been capped at a nice round number of 25Mbps. This would tend to indicate that DLM has kicked in to try and give a stable connection.
You should contact BT and ask that an engineer be sent out to investigate the problem. Once the fault has been fixed your speed should rise but it still won't reach the max on Infinity 1 so the downgrade would still be worth it.