Seem to have gone back to ADSL1

[#1]

I went on to ADSL2 a year or so ago when my exchange became 21CN enabled and was getting good sync speeds of nearly 3Mb/s but earlier this year I noticed speeds had dropped and my router was reporting modulation of G.dmt which I understand is ADSL1.  Attempting to reconnect with the router set to ADSL2 or ADSL2+ fails and only G.dmt works so I would be grateful if my line could be reset to ADSL2 again as that did seem to work better despite the length of my line and attenuation (generally 60/61dB) than G.dmt.  Why might my line have been put back on ADSL1 as I was not aware of any problems with connections apart from occasional low upstream speeds after mains blips etc.
Thanks in anticipation
Rod

[#2]

Hi there,
This seems to have happened around the start of last year following a change of account type because the estimates for your line now look lower than what I'd imagine you to have seen originally.
I'm raising an order now to get you back on ADSL2, I'll update your account with details of that shortly.