Another speed issue

[#1]

Over the last couple of weeks the real world web speed experience seems to have got progressively worse, however apart from one instance the bt speed tester seems to indicate things are ok.
My IP profile is 12000 up and 440 down.
Last 4 BT speed tests:
Sat 23, 11:45: 2281d, 359u
Mon 25, 08:55: 7019d, 358u
Mon 25, 15:45: 820d, 325u (worst results)
Mon 25, 19:55: 8772d, 353u
Tue 26, 07:45: 10171d, 356u
However I've also run the mybroadband speed test this morning 45 mins after the last test above at have got 832d, 365u which mirrors my experience of very slow downloads - it's taking 2 hours est. to download a 665Mb itunes/iphone update.
Any suggestions?
Router stats:
Data Rate
Stream Type Actual Data Rate
Up Stream 440 (Kbps.)
Down Stream 14336 (Kbps.)

Operation Data
Operation Data  Upstream  Downstream
Noise Margin 25.1 dB 6.5 dB
Attenuation 9.3 dB 22.9 dB

[#2]

A little more information...
Another BT speed test at 09:25: 5385d, 359u.
Mybroadband speed test at the same time 627d, 356u
BBC iplayer diagnostics attached...

[#3]

Hi KevH,
I've just ran some tests and I can't see any issues at this end (as you predicted). Have a look here for some tips on troubleshooting this kind of issue and choose the section "The download speed is too slow"
Jojo