Current speed estimate too high and wrong

[#1]

Hi folks,
I received this surprising notification today:
Phone exchange:
   COTGRAVE
Estimated line speed:
   1.0Mb (Accurate to within +/- 1Mbit) - Checked on 2012-05-18 22:23:42
Current line speed:
   7.15 Mb
My Line stats:

adsl: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 1
Max:    Upstream rate = 900 Kbps, Downstream rate = 3072 Kbps
Channel:        FAST, Upstream rate = 448 Kbps, Downstream rate = 3040 Kbps
Link Power State:       L0
Mode:                   G.DMT
TPS-TC:                 ATM Mode
Trellis:                ON
Line Status:            No Defect
Training Status:        Showtime
               Down            Up
SNR (dB):        9.3             17.0
Attn(dB):        63.5            31.5
Pwr(dBm):        18.1            12.1
The above synch is what I expected it to be. Any thoughts on why Plusnet are seeing 7.15?

[#2]

They aren't.
That is the default number until they receive an update from the BT systems - it is intended to follow the IP profile as given by the BT speedtest but sometimes the report doesn't come through properly

[#3]

Thank you.