Erratic speeds.

[#1]

I've been getting increasingly poor and erratic speeds over the past few weeks, generally around peak time with speeds picking up again after midnight.
The exchange shows as green, I'm on Plusnet Unlimited and nobody else is using my connection. The problems range from a single download running at 50kb/s crippling my connection (it's supposed to be 8mb so this shouldn't be happening) to ping response times of 1000ms+ on websites with no downloads/uploads going.
I was going to file a ticket but I thought I'd see if I can get some advice here first, here's a BT Speedtest I ran at 1715.

And some of the pings just to show response times, I know they aren't that helpful. All pings are to Google, usually they're about 34ms.
Ping statistics for 173.194.37.104:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 627ms, Maximum = 691ms, Average = 659ms
10 seconds later...
Ping statistics for 173.194.37.104:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 1096ms, Maximum = 1194ms, Average = 1155ms
Does anyone have any suggestions?

[#2]

I assume you are connected to the router by wire and not wireless

[#3]

Yep, forgot to mention that, it's a fully wired connection and I've tried switching routers out to see if that might be the problem but nothing changed.
jim:quote

[#4]

Only one thing I can think of to try - disable your firewall/antivirus and try the ping test again