This is not a very good start.

[#1]

Quote from: crabstix

Bandwidth (Up/Down) [kbps/kbps]: 443 / 12.495 SN Margin (Up/Down) [dB]: 29,3 / 6,1

As Anotherone says, your stats are now looking much better.  12Mb sync down and SNR of 6dB
If you follow his advice, of making sure that everything plugged into your extensions is definitely filtered, including Sky boxes, home alarms, phones etc.  Also, post which wires are connected to the back of the master faceplate
B.

[#2]

First of all my apologies for not spotting how to remove the blank lines.
The only items I have plugged into the test socket are the phone and modem, via the filter.
None of the coloured wires are connected in the master socket.
When can I put the faceplate back on the master socket?
Do you still say that Plusnet are checking my IP Profile, and that my final speed could be up or down on the current reading?

[#3]

Stay in the test socket for the time being, whilst the line is in training it's not good for resyncs to occur too often otherwise the exchange DLM may think you have a dropping connection.
The comment to which you refer was perhaps slightly misleading but was made in the absence of any stats. Unless you have an especially noisy line, I'd expect your speed to be very similar to now, possibly improve slightly.
If you could run the BT Speedtester (Diagnostic) and text copy and paste the results into a post along with the Current Line speed (login required) , we'll see what the overall picture is.

[#4]

Anotherone, I hope this information is what you are looking for.
Postcode:, 44, S35 9YNPhone exchange:ECCLESFIELDEstimated line speed:6Mb (This may vary between 5Mb and 8Mb) - Checked on 2012-05-24 22:30:35Current line speed: 7.15 Mb
BT Tester states:-
Download Speed = 6.75
Upload Speed    = 0.36 (which seems very low )
Ping Latency      = 35.00

[#5]

Ok, some of that information is OK, but you ran the BT Beta speed tester not the diagnostic one.
See this post I've just made, for guidance.

[#6]

Is this the information you require? Many thanks.
1. Best Effort Test:  -provides background information.
Download  Speed
7.4 Mbps
 
0 Mbps 7.15 Mbps
Max Achievable Speed
Download speedachieved during the test was - 7.4 Mbps
For your connection, the acceptable range of speeds is 2 Mbps-7.15 Mbps.
IP Profile for your line is - 7.82 Mbps
2. Upstream Test:  -provides background information.
Upload Speed
0.39 Mbps
 
0 Mbps 0.45 Mbps
Max Achievable Speed
Upload speed achieved during the test was - 0.39Mbps
Additional Information:
Upstream Rate IP profile on your line is - 0.45 Mbps

[#7]

There is something odd going on here, has your modem/router been on 24/7? If not, when did you turn it on last?
And can you post the current modem/router ADSL stats similar to (edited) reply #13.

[#8]

Anotherone, Can't be specific, but earlier today I had to take out the modem because my wife was getting excessive hiss/crackle on the phoneline, when she was talking to someone.
This is a problem I had with my previous ISP, and I had to take out the modem each time. I can't be specific when I reinserted the modem.
Here are the current stats from my router.
DSL Connection
Link Information
Uptime:
0 days, 4:05:34
DSL Type

ITU-T G.992.5
Bandwidth (Up/Down) [kbps/kbps]:
443 / 8.863
ta Transferred (Sent/Received) [MB/GB]
371,44 / 1,75
Output Power (Up/Down) [dBm]:
13,1 / 0,0
Line Attenuation (Up/Down) [dB]:
18,8 / 35,5
SN Margin (Up/Down) [dB]
29,5 / 12,1
System Vendor ID (Local/Remote):
TMMB / ----
Chipset Vendor ID (Local/Remote):
BDCM / IFTN

Loss of Framing (Local/Remote):
0 / 0

Loss of Signal (Local/Remote):
1 / 0
Loss of Power (Local/Remote):
0 / 0
Loss of Link (Remote):
-
Error Seconds (Local/Remote):
901 / 0
FEC Errors (Up/Down):
0 /0
CRC Errors (Up/Down):
4 / 2.230
HEC Errors (Up/Down):
0 / 3.483

[#9]

I hope you used the Disconnect method I mentioned in reply #10.
From what you've now said, you obviously have a fault, if it's already causing disconnects, you may get banded (restricted speed) or the Target Noise Margin gets raised to try and stabilise the situation, but again this is at the expense of speed. Further drops - abrupt loss of sync makes matter worse which is why you should use the Disconnect method. Looking at the stats - your Bandwidth Down is lower - 8,863 (so that limits your speed) and the SN Margin Down is 12.1dB so there is the possibility the Target Noise margin has already been pushed to 12dB.
From what you have described, in conjunction with the high HEC errors in just over 4 hours since you reconnected (& the CRC errors) you may be lucky and just have a faulty filter (the one the phone is plugged into) instead of a faulty line. Before dark or wait until tomorrow, Use the Disconnect procedure and change the filter. Mark the one you take out as suspect - bear in mind it may not be,  you'll only find out if the problems go away.. I hope your filters look like these.
Who do you pay your line rental for your phone line to?

[#10]

Anotherone, before I carry out this disconnection, can you advise what you mean by "Power Down"?
In fact, yesterday I simply pulled out the modem from the filter, as I have been used to doing previously.
I am paying Plusnet for my line rental.
Sorry to be a pain.

[#11]

Power down means pull the mains plug out. Good for the Line Rental, that makes it easy to get a line test done if needed, you won't have to talk to Mumbai !

[#12]

@crabstix
From what I can see, you seem to be suffering from frequent disconnections which will in turn explain the reduction in line rate. So I'm going to advise that you raise a fault so we can broach this with our suppliers: http://faults.plus.net
Adam

[#13]

He has not said that Adam, read the thread   He has saidi his wife has complained of some crackling and so he pulls the modem/router out which obviously fixes it. That suggests he has a faulty filter.

[#14]

Anotherone,
Your comments towards our staff are uncalled for and quite frankly rude.
Adam has clearly checked details which you do not have access to.
<img src="http://ccgi.psmith12.plus.com/visradius/generated/image1340107385830.png" />

[#15]

James read the thread and then ring me. When we are in the process of checking whether he has a faulty filter or a faulty line what is the point in suggesting he raise a fault to an already overworked CSC and Faults team. If it's clearly shown to be the line then that is the time to raise the fault.