Broadband Speed & Router Firmware Update

[#1]

Hi, over the past few months we have been receiving noticably slower speeds on our broadband. Where I used to be able to download in excess on 700kB/s (or 5.47+Mb/s), I am now only getting around 400-450kB/s (3.13-3.52Mb)
Having read the sticky regarding speed faults, I have provided my router details, the BT speedtest, and my line speed as stated in the member centre.
I'm currently unable to supply the 'further diagnostics' test as it limits to three tests an hour. Although, interestingly, it gave a maximum attainable speed of 4Mb/s for our number, and 7.15Mb/s (911.36kB/s) for our neighbours, who are also on plusnet, but use a different router.
Why is it they get a faster connection?
Why is it our connection has slowed down?
My other request is for a firmware update to be pushed to our Technicolor TG582n router, current firmware 8.4.4.J. I have tried various times on various devices and OS' using the tools provided here: http://products.plus-payh.co.uk/firmware/ to no avail.
Thanks.

[#2]

Hi there, thanks very much for posting all of your stats, it proves very useful
I've had a look at your connection and I've found out why your speeds are low. It's not router specific as far as I can see. Your line is
<a href="http://community.plus.net/library/broadband/broadband-faults-guide-banding-guide/">'Banded'</a>. Banding is automatically applied by DLM (Dynamic Line Management) - it does this if your line becomes unstable, this may well have been in the past. Depending on the amount of drops at the time, will depend on the level of banding applied and whether or not the banding will be removed automatically.
I've performed a reset on your line which will remove the banding for you and should improve the speeds you get. I've also updated the internal speed profile set on our systems. You might need to log into your router and hit the 'Disconnect' and 'Connect' button for the changes to take effect.

[#3]

Apologies for the late reply, I have been away from home and working.
Thanks for your help and I can confirm download speeds are again at 700kB/s+, with the two BT speedtests returning 6.29Mb/s and 6.75Mb/s download.
I was going to make a post in January after a day of constant connection and disconnection, but gave up on posting due to these issues and lack of mobile internet where I live.
Whilst I believe speeds were down before this incident, I imagine the following logs may show what caused the banding to be applied.
Do you have any insight of the actual cause of the issue shown in the attachments?
Also, is it possible to have a firmware update pushed to our TG582n router?

[#4]

The low speeds were being caused by the fact the your router lost it's connection (sync) to your Local Exchange for one reason or another. With broadband faults it could be a number of different reason for this to happen, so I'd not be able to give you a firm answer on that I'm afraid.
You can upgrade your firmware here though http://products.plus-payh.co.uk/firmware/ the upgrade tool is pretty easy to use, we've included a help guide in case you'd like a read up on it.

[#5]

In my original post I stated " I have tried various times on various devices and OS' using the tools provided here: http://products.plus-payh.co.uk/firmware/ to no avail."
However, having tried one final time to update the firmware it has now worked.
Thanks for your help on both matters