Yes you can show us a speed test at 1am, but that just as much shows wifi congestion is less of an issue at 1am as it does anything else.
Virgin have told you it's at 80% utilisation at peak time so it still has free capacity then I guess?
The 80% is an average across a 3 or 4 hour peak period, I can't remember which, no doubt with spikes higher and lower than this level.
The last time I heard the threshold for downstream was 90% for a week during this period. At this point the group should be prioritised for upgrade.
If the load has continued to increase I fully imagine the area has been sent to the planning group.
The area is still on a 10k due to issues with either space, power, cooling or transmission capacity at the hubsite. The OP is connected to a temporary solution to deliver 12 channels rather than the 10 the older 10k deployment was restricted to, and as soon as the issues with the above are resolved his node will be connected to an E6k or cBR-8, running between 16 and 24 downstream channels to his area, and the capacity issues will disappear.
There are pockets of congestion where people are connected to limited hubsites sadly. The good side is that as soon as the hub has been upgraded the problems will go away, the down side is that the upgrades are a time consuming PITA.