Miraculous Line Speed Improvement!

[#1]

I'm a new customer who was previously with Fast.co.uk (expensive but good) with a maximum line speed of around 2Mbps.
Imagine my delight when I received the following e-mail from Plusnet this morning advising me of my new, improved service:
"When you signed up for your broadband account, we performed a check on your telephone line to give you an estimated speed your line might achieve.
Now that your service has now been active for 14 days, we thought we'd let you know the speed as it stands today, by way of comparison.
Estimated line speed: 2Mbps
Current line speed: 7.15Mbps"
I've just done a speed check and, guess what: max speed 1966kbps, exactly the same as before.
I'm no techie so perhaps I'm missing something? Can someone please explain? 

[#2]

Could you post some stats from your router and the results of a BT speedtest

[#3]

Thanks for the very prompt reply, Strat!
As I said, I'm no techie so I may need some talking through here.  I've just done the BT speedtest and here are the results you requested:
Download speed achieved during the test was - 1860 Kbps
For your connection, the acceptable range of speeds is 400-2000 Kbps.
Additional Information:
Your DSL Connection Rate :2400 Kbps(DOWN-STREAM), 448 Kbps(UP-STREAM)
IP Profile for your line is - 2000 Kbps
How do I obtain router stats?  It's a Belkin N wireless router

[#4]

Have a look here http://www.kitz.co.uk/adsl/frogstats.php

[#5]

Quote

I'm no techie so perhaps I'm missing something? Can someone please explain?

Don't get excited its just 2 computer systems not talking to each other!. The BT systems are 'supposed' to send PlusNet details of your actual line speed after the initial connection period, or afterwards when it changes. The PlusNet recorded line speed is set initailly to the highest possible ( 7.15Mbps ) and then updated when the BT systems send the information. In your case it just looks like that information has got 'lost'.
Its still worth posting your router stats, then we can see if your line speed is reasonable for your line, you can get details of how to get the stats from most routers here  http://www.kitz.co.uk/adsl/frogstats.php
Edit: beat me to it Strat.

[#6]

I thought it was too good to be true but a mate who lives only 300 yards from me gets 4Mbps which I do not understand. 
Are these the stats to which you refer?
Type Interleave Path 
  Status SHOWTIME
   
Downstream Upstream

  Data rate(Kbps)
2400Kb 448Kb

  Noise Margin
7 15

  Output power(dBm)
119 181

  Attenuation(dB)
61 31
Thanks for your kind help and advice, gentlemen.

[#7]

With that kind of downstream attenuation this says you're likely to get around 2.3Mb/s which is about what you are getting.
Have you tried a speed test when plugged into the test socket if you are not already in there?