How do I know I am on ADSL2+?

[#1]

I have a Netgear DGN2000 router.  Is there any way to tell if I have been switched to 21CN?
I have checked the router and can't find anything to tell me.  Routerstats doesn't help and I don't want to install dgteam firmware unless I need to.
Plusnet speedtest result:
Today 16:31 3952 kbps (494kB/s) 869 kbps (109kB/s) Share
Dec 31, 13:15 2826 kbps (353kB/s) 364 kbps (45.5kB/s) Share
Since joining Plusnet years ago we have had a rock steady 3 Mb connection.
I got a ticket saying the line would be automatically upgraded to (upto 20Meg) and I replied saying no thanks.
I thought that as the line is at least 4 miles long to the exchange I was doing good getting a 2-3 Mb speed.  All of a sudden it's gone up

[#2]

Since your measured upload speed on MyBroadbandSpeed is above 448kbps (and even 832kbps) is looks like you are on 21CN with upstream uncapped. To confirm this do a full performance test (not the beta) at http://www.speedtester.bt.com. If your IP Profile is *not* a round number and it does an upload speedtest for you then you are on 21CN.
It looks like switching to 21CN and ADSL2/2+ has been significantly beneficial for you.

[#3]

Thanks.  I raised a ticket when they told me 21CN was going to be available asking not to be switched which they agreed to.
I was worried with the long line I would not see any better speed and that it might even make it less stable.
I'll just have to see how it goes but so far it looks like I was wrong asking not to be changed.