BT Lowering Target Signal to Noise Margin

[#1]

Following recent problems my Target Signal to Noise Margin was increased from 6 db to 12 db.
During the following 15 days I lost sync once and manually re-synced once.
I lost sync again this morning and to my surprise the Target Signal to Noise Margin appears to have dropped to 9 db.
I experienced a BT fault several years ago, and I have never known BT reduce the TSNM without being pressed very hard to do so, although I believe their systems are supposed to do this automatically following a period of stability.
Can anyone confirm that BT's systems are working better than they used to in this respect.
Perhaps I have just been lucky or could something else be happening.
To my knowledge BT have not been investigating my fault since raising my TSNM 16 days ago.

[#2]

Yep - It can reduce after 28 days of stability.
If you're patient though, we should be able to reduce your SNR (ourselves!!) in December, when BT make it possible for us to do so.
Otherwise, put a request on your fault ticket and a member of the faults team should pick it up for you.

[#3]

You guys get better by the day
Many thanks for the incredibly fast response and the info.
I watched as BT tweaked the TSNM up and down 16 days ago and settled on 12 db.
Perhaps BT are getting better too.

[#4]

I had a line fault - JCB'd cable - in May, subsequent to which my long standing 6dB margin went up to 12dB. Despite a low error count, it stayed there until October, when my local exchange had a MUX fault.
On restoration, the margin dropped to 9dB within minutes, then dropped again to 6dB within a few hours. Go figure! 

[#5]

12db... I can only dream of 12.  Mine is 16.0
Starting to feel sorry for myself and a fool:
1. No competition so I have to pay full price and subsidise others.
2. No competition so no plan to upgrade exchange to 20Mb/s.
3. Reduced maximum download speed because of increased S/N.
Got to love the 'free' market - sorry, private monopoly on local loop.