Confused by speed results!

[#1]

Hi,
I've been with plusnet for 5 years and have had and continue to get good service.  I just moved to Plusnet Pro and so from adsl1 to adsl2+.  I live in a semi-rural area and was told to expect a speed of around 3Mbps.  Beofre the move to the 21CN network I was measuring speeds around 2.2Mbps on speedtest.net. I was using a Draytek Vigor 2600Plus.  After the move to 21CN and using the same router (which is only adsl1 capable) my line speed jumped to about 3.8Mbps and I was measuring speeds of up to 3.4Mbps just a few days after the change.  A few days later still my speed had dropped back to around 2.7Mbps (so I guess my line was training itself) - still better than it had been before though.
I bought a Draytek Vigor 2800V adsl2/2+ router, hoping that I might see even higher speeds.  I'm not seeing any change in measured speed, but I do see different line speeds depending on the mode I set it to.  In ADSL2+ mode, I see a line speed of around 3.25Mbps and a snr of around 8dB.  In ADSL2 mode, the line speed is around 4Mbps but snr is lower at around 3 or 4dB.  No matter what mode I choose, my measured speed (both on speedtest.net and the bt speed tester) is never higher than 2.75Mbps.  My ip profile is 3000, by the way.  I'm surprised to see such a speed difference between adsl2 and 2+ - why would this be?
Now, if I hadn't had seen speeds as high as 3.4Mbps for those few days, I would think this probably all more or less makes sense.  I would imagine that my ip profile of 3000 is dictating a maximum speed around what I am seeing.  So my questions are a) how did I get a higher speed of 3.4Mbps and b) will my profile change again now that I am on the 21CN network?  If so, when is this likely to happen - am I right in thinking it happens every fortnight or so, or does it have to be manually kicked off?
Any useful hints greatly appreciated!

[#2]

welcome to the forums after all this time
It sometimes happens that although on 21cn, you dont automatically go on to ADSL2, if you do a bt speed test, that indicates if indeed you have moved over  http://speedtester.bt.com/  One of the comms team should see this later on today and can move you over correctly if needed

[#3]

Hi there,
Your profile changes to 3000 not long after the move to 21CN, so I can only assume that the speedtest of 3.4Mb was before that (or an inaccurate test).
Your profile will change if your line stays stable and at a speed which will support a higher profile. What are your router stats at the moment?

[#4]

Hi Mand,
I thought my profile changed to 3000 on the 4th or 5th of this month, i.e. before the move to 21CN .  The test at 3.4Mbps was definitely after the move.  I got that result consistently over a couple of days so I don't think it was a mistake.  I didn't actually look at my ip profile during that time, so maybe it had gone up?
Now, my ip profile has dropped overnight to 2500 and my measured speed is around 2.4Mbps, so I am now more or less back where I was on adsl1.  My router reports that I am on adsl2+ with down speed 355830 and up speed 444900. snr is 6.0 and loop att. 46.5.  My down speed is pretty consistent - it's never been below about 3.25Mbps since the move to 21CN so I don't understand why my profile has now gone down to 2500.  Can you look into this?  Is my fiddling around with router modulation settings likely to have upset things?  I'm still not clear what triggers a re-profile - can you say?  Do I now have to wait 14 days for it to happen again or can it be forced?
Thanks.