They have just rung and I am back on an adaptive profile!!!! Stats are below:-
Well that has always been the case.
Max DSL (BT or LLU) is rate adaptive by default and is very rarely set at a fixed rate manually by the ISP (unless to provide a certain fixed speed using DSL Max exchange equipment hardware).
Often a certain sync speed is maintained either by not rebooting/resycning the router and the line conditions at the time of sync noise margin vs. target noise margin. If you have consistent resyncs/lose of sync the target margin is raised and can sometimes remain so (which looks to be the case with your stats of 4096Kbps with 17dB margin).
If the ISP resets the profile, it will be trying afresh from the default target SNRM compared to the one decided over time by DLM and so a sync speed increase can be expected.
If you leave the router on, it will continue to adapt to changing line conditions and so if the SNR drops too low may resync. After a few resyncs this may lead to an increase in SNR margin and hence lower speeds.
If you only use the router when the SNR is at its best, it is likely to retain the 9dB margin and provide a higher sync speed. However, the DLM may think the router being disconnected is due to signal failure and may tamper with the settings as a result.
Overall its best left as it is, leave the router on, it is set to a target 9dB noise margin which will only change if you have major sync loses.
If I were you I would now be content. The line has had its profile reset and is a decent speed anyhow. If your satisfied with your ISP, then you can save sending out 300 change of e-mail address notifications and if not, then switch to an ISP with better customer service.
As for the GCSE's, I did them four years ago and still had plenty of time for other things.