Broadband Speed sub 0.5mbs - recent change

Question

Hi
My broadband speed has recently plummeted. No storms or anything have occurred to reset the sync, but this is what seems to have happened. I have an open fault  but have heard nothing. Please help! The line has been fine for years
This is the speedtester result:
Download speedachieved during the test was - 251 Kbps
 For your connection, the acceptable range of speedsis 100-500 Kbps.
 Additional Information:
 Your DSL Connection Rate :460 Kbps(DOWN-STREAM), 804 Kbps(UP-STREAM)
 IP Profile for your line is - 350 Kbps
The throughput of Best Efforts (BE) classes achieved during the test is - 10.74:22.45:66.81 (SBE:NBEBE)
These figures represent the ratio while sententiously passing Sub BE, Normal BE and Priority BE marked traffic.
The results of this test will vary depending on the way your ISP has decided to use these traffic classes. 
And these are my ADSL stats (asus router)
Statistics -- ADSL
Mode:
ADSL2+ 
Line Coding:
Trellis Off 
Status:
No Defect 
Link Power State:
L0 
Downstream
Upstream
SNR Margin (dB):
31.2 
9.8 
Attenuation (dB):
43.0 
23.3 
Output Power (dBm):
15.6 
12.4 
Attainable Rate (Kbps):
6060 
19290 
Rate (Kbps):
462 
770 
MSGc (number of bytes in overhead channel message):
61 
19 
B (number of bytes in Mux Data Frame):
14 
38 
M (number of Mux Data Frames in FEC Data Frame):
1 
4 
T (Mux Data Frames over sync bytes):
1 
2 
R (number of check bytes in FEC Data Frame):
16 
16 
S (ratio of FEC over PMD Data Frame length):
0.9688 
6.4000 
L (number of bits in PMD Data Frame):
256 
215 
D (interleaver depth):
32 
1 
Delay (msec):
7 
1 
Super Frames:
46296 
46294 
Super Frame Errors:
0 
303 
RS Words:
3101886 
786998 
RS Correctable Errors:
415 
15 
RS Uncorrectable Errors:
0 
N/A 
HEC Errors:
0 
8 
OCD Errors:
0 
0 
LCD Errors:
0 
0 
Total Cells:
819682 
5439847 
Data Cells:
40108 
40965 
Bit Errors:
0 
155 
Total ES:
0 
7 
Total SES:
0 
7 
Total UAS:
17 
15793 

Answer 1

IMJolly, I appreciate your help, and I'm not nagging at you. I see that you go out of your way to assist people on this forum and I am gratified for your response.
I'll be leaving the router on for the next few days to see if there is any improvement, but as it happens, I am geeky enough to check my router stats every day
That's how I know the exact date the connection bombed out (Saturday 4th September). On this date i noticed that the SNR was considerably higher than normal and thusly I guess the sync was bumped to it's lowest level, for whatever reason.
I will be replacing the microfilter as this may be a problem, but I am still pretty much convinced, judging by the number of related posts here that there is a general problem with something being rolled out, or a general BT fault at the exchange that is not being acknowledged. Shame I don't know my neighbours to see if they're with BT and suffering the same problem.
I really do not want to waste any time with the call centre, what's the best way of escalating this in your opinion? I do need someone to look into this or I'll have to fight cancellation charges in court and go elsewhere.