v slow connection and v confused

[#1]

Yes, I know I'm yet another newbie with a speed problem but try as I might, all the links I can find on this site and forums just seem to be confusing me more.  Here's the symptoms:
Been running just fine for speed, pretty much since I joined Plusnet, so I've never checked my speeds.  Then last Friday on return from hols I noticed drastic drop in speed suddenly down to dial-up rates.  Read the "Got a speed problem" sticky and checked a few things out:
BT Test results :
IP profile = 135kbps
DSL connection rate: 448 kbps(UP-STREAM)  7360 kbps(DOWN-STREAM)
Actual IP throughput achieved during the test was - 116 kbps
According to my account page at PN:
your current broadband speed is 500 Kbps  (constant since last Friday 21/2)
My speedtouch 510v4 router give following stats:
Output Power (dBm) up/down =  12.0 / 19.5
Attenuation (dB) up/down = 9.0 / 14.0
Noise Margin (dB) up/down = 23.0 / 11.5
There have been NO changes in connections to my BT line at all.
MY QUESTIONS: 
What can I (or PN) do about it?
Should I be reporting this to BT?
I've seen the stuff about how bad connections can cause BT to cut your profile but does this test result mean I've still got a crap line and it won't improve?
<beginAside>
I do find most of the supposed help info on PN very confusing and conflicting.  A few examples:
*  my current broadband speed is 500kbps and is based on my sync speed, but I can't find where to get my actual sync speed anywhere.
* your sticky on speed problems is mostly techie garbage to me.  I really want some simple instructions and explanations.  When it does tell me something factual - to look at a table on this page (http://www.plus.net/support/broadband/products/faqs_and_guides/dslmax_guide.shtml#Sync) to find relationship between synchronisation speeds versus the appropriate IP Profile speeds.  It's a shame the table - indeed to whole page - has no mention of IP Profiles at all.
<endAside>

[#2]

Hi,
Your sync speed will be the 7390kbps figure which is labelled DOWNSTREAM on the BT test. As this is quite high, I would expect the IP profile (or line profile) set by BT to be 7000 however as it is 135 it brings up a certain other question. Have you had any disconnections recently that you are aware of or has it been constantly connected?
I ask this as usually when the line is unstable, BT drop the IP profile to 135 in order to make it more stable. Now obviously that is a lower speed than you should get but if you genuinely do have a dropping connection issue, this will need to get fixed first. Once that's fixed, you will find the speed increase.
What I would advise to do is to check if you have had lots of disconnections in the past few days and if so, raise an Intermittant Fault via our Faults Checker at http://faults.plus.net. If you have not had any disconnections then raise a Speed Fault at http://faults.plus.net. Please ensure that at least 3 speed tests are carried out at http://www.speedtester.bt.com prior to this so we can read the results in the database and advise with all the available information.

[#3]

Hi Brad,
The PC is on all the time so no manual re-connections.  I recall that the line was dropping periodically a couple of weeks ago, but remembering that I'm new to this stuff, where do I find out my connections history? 
I also have some results at mybroadbandspeed for prev 24hrs.  download is choked at 130kbps, upload varies from 383kbps (mon lunchtime and just now) down to 131kbps at 01:54 yesterday.
Continuing my education: if PN reports my "broadband speed" as 500kbps, how does that relate to a sync speed of 7390kbps?
Simon

[#4]

Hi Simon,
Thanks for taking the time to speak to me this morning.
As discussed, I've now raised a fault regarding your profile being stuck.
Should you wish to do so, here's the article I was referring to:
link:speed

[#5]

Quote

from original post.... Then last Friday on return from hols I noticed drastic drop in speed suddenly down to dial-up rates.

I wonder if you switched off for a week (fortnight) holiday, if so, would that make a difference ?  Presumably if switched off, the exchange would register that as a "fault" and so drop the line ? 
Just a thought.... not techie enough to answer ....

[#6]

No, absolutely not.
There's no fluctuation in synchronisation speeds, hence no sync blips, so the IP Profile would remain constant.