Plusnet and downloads - driving me mad

[RRH]

I stupidly moved from BT Infinity to PlusNet last August... to save a couple of quid

Anyway, can someone cleverer than me explain this..

Line can support c80 meg.

Speedtest usually reports about 70 downstream, 20 upstream, ping around 30m/s.

That said, downloads are VERY slow. Doesn't seem to matter what time of day, whenever I try and download from megashares / rapidgator etc, I'm doing well to get 300k/sec with frequent stalls. The BT infinity connection was always 2mb+ and v v stable.

Any thoughts? Not sure what could be up with it as I don't understand anything beyond the speedtest results.

Any help would be greatly appreciated!

[RRH]

I subscribe to both the file sharing sites referred to- only having probs since I moved to Plusnet.

[RRH]

Downloading at 5.3 mb/s this morning so must be 'traffic shaping'

[RRH]

I'll sport a fiver and let you know!
Thanks for your help.