20 Mbps decrease in my fibre speed

[#1]

I have just noticed when I got home tonight that the throughput on my FTTC has dropped from about 58 Mbps to a consistent 38 Mbps.  Interestingly the download speed I would expect from my old 40/10 service.  This does not feel like a network congestion issue.
I have restarted everything with no change.  My IP profile per the BT speedtester is 54.12 which is about 5 Mbps lower than before but putting that aside my download rate is inconsistent with the IP profile.  I am concerned because when I was first put on the 80/20 trial something went wrong and I was stuck on the same 40/10 speeds for weeks before everything was fixed.  I am just hoping the problem hasn't reappeared.
The other thing is that my line speed per the members centre is 40 Mbps.  This was set at the unlimited 20 Mbs rate before.  I am uncertain if the 40 Mbps is capped at 40 Mbps as it was originally or if is now uncapped in the same way as the 20 Mbps setting.
My line has been extremely stable for months before today.
Could someone from Plus take a look please?

Thanks.

[#2]

This is currently being discussed on the main 80/20 trial thread at the top of the page - if you raise a ticket specifying exactly what has happened it should be fixed - mind you, Adam implied on the other thread that they had all been fixed anyway.
Edit: not quite, quote from Adam Walker: "FYI we've identified all the affected trialists now so we're working towards a solution."

[#3]

Thanks for the quick reply Kevin.
I haven't been keeping up with the board recently but now I have checked I see there are tons of posts about this issue in that thread.  I'll raise a ticket.
Cheers.

James
[Edit: Now raised on ticket #57497873]