Sync speed keeps dropping

[#1]

I had FTTC with BT for 18 months and maintained a sync of about 78000 down and 19999 up pretty much the whole time, when I first switched to Plusnet it was the same but the last few weeks my connect has dropped a few times and my sync speed is dropping like a stone. It is currently sync'ing at 59504 down and 18999 up.
Also I'm pretty certain that my traffic is being throttled, especially the upload speed. Plusnet make it clear they do not do this, but I'm certain this is not the case.
Can someone check that there is not a problem with my line as I have had no problems in the past with BT so I don't think the fault is at my end as none of my equipment has changed.

[#2]

I thought I'd clarify on the throttling a bit, so I've been using Torrent Sync (http://labs.bittorrent.com/experiments/sync.html) as me and some friends have been working on a video project for a short movie and its a great way to keep files in sync with each other when we are now scattered over the UK since leaving Uni. I noticed that the upload speed is fine for a short while, like up to 1.5MB/s but after about 5 - 10minutes the speed drops to 100kb/s or so, if I switch ports then it will shoot back up to full speed again and then drop after a few minutes. So something weird is definitely happening.
I did notice my traffic usage is a little high because of this, but PlusNet say there is no throttling or usage limits and I had no problems when I was with BT aside from they did throttle this traffic in peak times but they advertise this fact and was one of the reason I decided to switch to PlusNet, aside from the cheaper prices.

[#3]

PN don't apply any kind of traffic management to upload stream. Could it be a setting in Torrent Sync affecting your upload speeds?
The loss of connectivity might explain why your IP Profile has been reduced. It could be that BT's DLM system picked up instability on your line and reduced your speeds to provide more stability.

[#4]

As I said my line has been rock solid for 18 months with BT, I thought it might be a problem with my modem/router which is a Draytek 2750n. Apparently I'm not the only person having these issues since the last few weeks:
http://www.forum.draytek.co.uk/viewtopic.php?f=2&t=18856
That person said

Quote

BTOR have been rolling out new firmware to their modems over the last couple of weeks. They also appear to have been making some changes to the DSLAMS as well - there are adjustments being made to the band plans for the spectrum's for the upload and download frequencies. Who knows whether the changes at the DSLAM end is affecting your Draytek modem's side...........

So have BT been faffing with my junction box and that has affected the stability and speed of my line?

[#5]

Here is a speedtest of when my line was fine:
http://www.speedtest.net/my-result/3028512298
Here is a spedtest from today:
http://www.speedtest.net/my-result/3083322311
All metrics relating to line, download, upload and ping are worse and nothing has changed on my end so either the bad wind lately has affected my physical line, or BT/Plusnet have changed some software/hardware/firmware that is affecting me with dropouts and worse speeds/ping than I've had the last 18 months with FTTC.