I'm experiencing significant peak time slowdown in my download speeds recently. I'm on the 600Mb/s configuration.

This only started after a short power break in our local area (SK10 5xx). Prior to that I could get 600Mb/s+ at any time of the day or night.
Here's my issue/question.
My area/network segment seems to have 40 downstream channels allocated.
Before the outage my modem was locked to channels 1-24. Since the outage it's locked to 17-40 and no amount of power cycles / factory resets seem to change that.
So it would seem that in my area channels 1-16 have much lower utilisation than channels 25-40.
(Channels 17-24 seem to be utilised in both situations).
Is there any way to get moved back onto the 'good' channels?
For the conspiracy theorists amongst you, do VM actively manage the local network segments in this way?
Also, what is the maximum number of downstream channels that can be allocated to DOCSIS given the requirement for TV?
For completeness I'll post my modem stats in a follow-up