Oddly, I am querying upstream!

[#1]

That isn't done often, but there is no problem with downstream performance.
Here is today's BT Test report for upstream
My 582N for 9 days has reported u/s sync 573 kbps, way below the IP profile, and for some reason, although today's throughput speed is logical, yesterdays was above sync rate. Something doesn't seem quite right.
BTW ping is high at ~45ms

[#2]

Your upstream has a medium level of Interleaving on it, which will decrease it's rate. The IP Profile is unlikely to update to reflect it on the upstream.
There are a few different levels of Interleaving, Low, Medium and High (1,2 and 3 respectively). The higher the level, the more speed you'll see dropped on the upstream. Also, the higher the Interleaving level the more (slight) latency you'll see. I believe the difference between each level is 2-3ms but it can depend on the type of traffic and the amount of traffic being passed.
We can reset the line and have the option to change the Interleaving Level to Low or even off, however, it looks as though Interleaving is on for one reason or another.

[#3]

So, interleaving is being applied to my upstream, which is odd, as the router's telnet data show depth 64 down and 0 up. Doesn't 0 depth mean not interleaved? Are you sure upstream is interleaved?I have telnet data, pre and post the last resync, and those do show that proportionately to duration, there are less now.
Anyways, let's try a reset and see how it goes from there; please.

[#4]

I think the upstream interleaving isn't necessarily reported properly. 
My upstream was slow initially, first due to capping, then due to interleaving. Now reasonably acceptable as interleaving has been turned off both up and down.
Oddly, my downstream has adjusted, via DLM, to 3dB margin and is pretty much the same as it was at Be before moving to PlusNet.
However upstream is stuck on 6dB so is still somewhat slower than before; I've no idea why that can't go to 3dB as well, but I've read that it can't. 

[#5]

Hi lucerne,
I've performed an SNR reset on your line and turned interleaving off which should resolve the issue for you.

[#6]

Hi Linn! Thank you for prompt action! Can you just confirm that it is only the upstream that has been turned off. I would prefer that downstream were kept interleaved.

[#7]

Unfortunately we only have the option to have Interleaving either On or Off on the downstream/upstream.
If your downstream needs Interleaving applying DLM should just stick it back on for you.

[#8]

Interesting as the removal of interleaving never seemed to take place (though I am not concerned about that now). In course of some matters I disconnected and powered off the router. On reboot four days ago the upstream speed was back to normal.