Fibre Upload Speed Dropping 10.52 to 9.5 to 8.5 to 7.2 to 5.2 to 3.79

[#1]

Had FTTC for just over two years. now on Fibre unlimited.  Over the past 3 months upload speed has dropped from approx 10 in January to 3.79 today. The speed has halved in 4 days from the 7.98 on 19 March. The download remains around 40 Mbps although it was approx 50 until that dropped in September 2013.  Why would upload drop significantly without any drop in download speed.  I have raised a fault ?
I am unable to run the full diagnostics test on http://speedtest.btwholesale.com/ as it says "Your speed test has completed and the results are shown above, however during the test an error occurred while trying to retrieve additional details regarding your service. As a result we are unable to determine if the speed you received during the test is acceptable for your service. Please re-run the test if you require this additional information." every time. I also have random disconnects and the i light with the little circle on the front of the Netgear Modem 150 modem goes Orange before reconnecting and going green. Once I noticed the DSL light go off on the Fibre modem at the same time but only but only the once. There is no noise on the telephone line.
 

[#2]

Full Diagnostics test is working this morning the results show :
Download speedachieved during the test was - 40.83 Mbps
For your connection, the acceptable range of speedsis 40 Mbps-40.24 Mbps .
Additional Information:
IP Profile for your line is - 40.24 Mbps
Upload speed achieved during the test was - 3.95Mbps
Additional Information:
Upstream Rate IP profile on your line is - 20 Mbps
So why has the upload dropped from approx 10 to 3.95Mbps over a week or so ?

[#3]

Can you try another site for uploading test? These two are much better (the BT Wholesale speed test can give erroneous upload results at times):
http://www.thinkbroadband.com/speedtest.html?utm_source=mainsite&utm_medium=navigation&utm_campaign=...
http://www.speedtest.net/
You can post the results as images on here.

[#4]

I get the same results from those sites. I have had a Sam Knows white box monitoring my connection for just over a year now so have various reports and figures I can pull off that which is handy for when problems occur. Upstream on 19 March was 8.02 Mbps then over the following  days it was as follows 8.03, 8.01, 7.98, 7.23, 5.29, 3.83 to 3.88 today.

[#5]

Can any one from Plusnet support give any advice or comment on this ?
I can't find anything relating to or explaining a big drop in upload speed on the support pages, whilst download remains unchanged. I haven't yet had any response to the fault ticket I raised on Saturday morning although I realise the weekend slows up action on faults.

[#6]

Hi DuncanM,
I've just taken a look at your line and whilst your download rate looks pretty much fine, as you've said your upload speeds are quite sporadic.
your upload rate doesn't match up considering your downstream rate. Would you be able to raise a fault with us at http://faults.plus.net and in the last box at the end of the troubleshooter, explain that the issue is regarding low upload speeds?

[#7]

Hi,
I have already raised a fault on Saturday morning ref 83198194. Something has been reset apparently on my profile about 10am this morning according to an update on the fault but I have just got home and it hasn't made any difference. I did mention in the fault  I raised that the problem was upload speed but I dont think the person who is dealing with the fault has read it properly. 

[#8]

I have just run the BT speed test as instructed and the results havent changed :
Download speedachieved during the test was - 41.23 Mbps
For your connection, the acceptable range of speedsis 40 Mbps-40.77 Mbps .
Additional Information:
IP Profile for your line is - 40.77 Mbps
Upload speed achieved during the test was - 3.84Mbps
Additional Information:
Upstream Rate IP profile on your line is - 20 Mbps

[#9]

Your Fault Ticket is due to be picked up within the next 24 hours.