Declining Fibre Speeds

[#1]

Hi all,
When I started getting fibre with PlusNet I got speeds of 53/14 Mbps. This gradually declined to 43Mbps down (I put this down to contention) so I switched to the 40/20 service and got a download speed of 38Mbps as expected.
But recently it's dropped further to 32Mbps.
I was using an ECI BT modem and I think I'm on an ECI cabinet while all this was happening. I've just switched to a Billion 8800NL so I could see the line stats and it's currently telling me the following:
Downstream Upstream
Line Coding (Trellis) On On
SNR Margin (dB) 13.1 6.4
Attenuation (dB) 21.2 0.0
Output Power (dBm) 12.1 6.9
Attainable Rate (Kbps) 59713 12807

Rate (Kbps) 34998 12549
http://speedtest.btwholesale.com/ states my profile is 33.87 Mbps
I don't know where the SNR values stands but the SNR Margin of 13.1 seems to have some head room in it.
So my question is, is there anything that can be done to get back to the higher speeds? On the 28th I should switch to the 80/20 service in the hope that I'll claw back some of the lost speed. Is this a possibility? Will it reset the profile? Will I get anywhere near the attainable rate of ~60Mbps down?
Thanks for any comments.

[#2]

Similar situation to me my friend
http://community.plus.net/forum/index.php/topic,144013.0.html

[#3]

Yes livelee, similar but you seem to be regaining some speed at least with the HH5. I'd hoped the Billion would do the same for me but not so far. I've read that the DLM can take as much as a month to increase speeds, which is a bit of a joke.
Plusnet currently say this :
Phone exchange: NORWICH WEST
Estimated line speed:46Mb (Download speed could vary depending on line conditions. Estimates are the maximum speeds that your phone line can support. These speeds are dependent on the package you choose.)  - Checked on 2015-09-20 11:49:59
Current line speed:33.8 Mb
If I go through the sign up for a new service on BT they think I can get 47-66 Mbps, so why I'm on 32 is beyond me at the moment.
Currently interleaving is on with a depth of 1123 (probably a hang over from before I switched to the Billion a couple of days ago), but even on a Sunday evening download SNR is 12.9 so there's scope there for more speed.
Hopefully a Plusnet rep will see this and give their hamster wheel a kick 😉

[#4]

@Jax, for what it's worth, 34998 kbps download suggests your line had been banded by DLM (one of the bands has a limit of 35Mbps).
Without banding, FTTC generally works at 6dB target SNR margin for the vast majority of lines.
If the cause of DLM banding has been removed then your line should improve (as and when DLM decides to do it), have you got any error stats?
Some information here: http://community.plus.net/library/browsing/fttc-dlm-what-it-is-how-it-works/ (not sure if this is completely up to date).

[#5]

Thanks w23, you may be right. My connection has increased, according to the BTW Performance test.
Download speed achieved during the test was - 37.72 Mbps
For your connection, the acceptable range of speeds is  30.97 Mbps-38.71 Mbps .
Additional Information:
IP Profile for your line is - 38.71 Mbps
My connection speed according to the Billion is 39994, with a SNR of 11.4
PlusNet switched me over today to the 80/20 service so hopefully that will kick in soon, DLM allowing.
According to DSLstats 5.6 my errors are:
                                    Downnload        Upload
RSCorr/RS (%):          0.0035         0.0038
RSUnCorr/RS (%):        0.0000         0.0000
ES/hour:                        1.69              1.57