Broadband speed slower than expected

[#1]

I've left the router on for over 72 hours, rebooted this morning and the speed has increased
as expected:

Here is the info from the router:
Line mode G.dmt
Line state Show Time
Latency Type Interleave  
Line Up Time 00:00:11:56
Line Coding Trellis Off  
Line Up Count 1

Statistics          Downstream Upstream
Line Rate   5984 Kbps 448 Kbps
Noise Margin 7.2 dB 19.0 dB
Line Attenuation 31.0 dB 22.0 dB
Output Power 19.6 dBm 11.9 dBm
And from PlusNet:
Phone exchange:
    BILLERICAY
Estimated line speed:
    5 - Checked on 2009-09-11 10:17:16
Current line speed:
    4000
Is this now the best I can expect out of my system?  Already a vast improvement. 
Thanks everyone for the assistance.

[#2]

your profile can probably go up to 5000 in the next 7 days

[#3]

Does that mean I have to do something or is that automatic? 
Apologies for my ignorance.
Mark

[#4]

just wait, but you could do one router reset in the morning each day

[#5]

Profile now 5000:
Phone exchange:
    BILLERICAY
Estimated line speed:
    5 - Checked on 2009-09-11 10:17:16
Current line speed:
    5000
Router stats:
                    Downstream Upstream
Line Rate 6208 Kbps 448 Kbps
Noise Margin 8.5 dB 18.0 dB
Line Attenuation 31.0 dB 22.0 dB
Output Power 19.6 dBm 11.9 dBm
and connection speed improved again:

Thanks everyone for your help.