Long term sync speed problem

[#1]

Only one router reports fluctuating SNR margins (Zyxel).  The other router reports much more steady at around 14dB (2wire).  It's bound to change a bit isn't it?
Both routers connect at approximately the same speed though.
Anyway we have made an appointment for Openreach/BT to visit tomorrow to look at the problem.

[#2]

Well the guy from Openreach has been and gone.  He found a fault in the dropwire where the cable had corroded badly and actually broken.  He fixed this and there was no improvement in the sync speed.  His modem actually connected 100Kbps slower after the repair, mine connected at the same speed as before.  Before and after this repair the line tested OK btw. He swapped the connection between the cabinet and my house too.
Apparently he is only supposed to spend 2 hours looking for a fault and is only allowed to swap connections over once if the test indicates no fault.
He mentioned a reference test (which gave 3.2M).  Does anyone know what this means?  He also managed to sync at 3.5M in the next road, about 200m away.   He also said that the RAMBO may reset after a day and give me better speeds.  Does this refer to the target SNR margin?  If so, I doubt it will reset in a day.  It's been at 15dB since I have been monitoring starting in April.

[#3]

Hiya,
I strongly suspect that he is referring to a combination of your line profile and the target SNR on your line.
I'd suggest monitoring it and rebooting your router first thing tomorrow morning when the line is likely to be quietest.

[#4]

Thanks James.  I've seen IP profile on my line fall and rise but never a change of target SNR margin.
Another rant:  I've just seen the update on my ticket suggesting that the problem is solved due to a rise of 32Kbps in sync speed.  Sorry but there's smoke coming out of my ears right now 
Yet another rant: Why can't the engineer stay long enough to fully investigate the problem?  It's very inconvenient to have to keep taking time off work for appointments.

[#5]

Resynced at 2144K this morning (i.e. lower than yesterday)

[#6]

Hiya,
Sorry the engineer visit didn't achieve anything
I've passed your fault back to BT.

[#7]

Thanks again James.
Can anyone from PN comment on my point above ("Yet another rant")?

[#8]

Because it's how the charging is based.
I'm not saying it's ideal, or particularly sensible, but the SFI charging model is based on 2 hour engineer slots.
It doesn't really sound like the engineer managed to achieve anything, other than replace a telephone socket in those two hours, so I'd be hopeful the next one is more productive.

[#9]

In my company we have to finish every job we start, which can often mean spending more time than expected.  This seems to be the only sensible way to operate IMHO.  If the charging model is based on 2 hour slots why can't another slot be used if it is needed?
BTW: The socket was replaced on the first Openreach visit (for a voice fault).  The second openreach visit was for the broadband.  He replaced a short length of cable at the pole and tested between the cabinet and my house but run out of time to do any more.  If the fault lies elsewhere it could take several more visits to sort out.  I don't have that much holiday from work

[#10]

Because they have another customer booked in the next 2 hour slot. 

[#11]

BT have dropped the target SNR margin down to 9dB (was 15).  Now syncing at 3M.
Now to wait for my IP profile to catch up