Are you saying tech support have given up? That shouldn't be the case - they should refer it to the next level for deeper analysis.
Regarding the issues you mentioned:
Volume control screwed up
Some people experience a lower volume from the TV Box. Others report that the remote control doesn't control the TV features, so they have to use their own TV remote. These are inconveniences rather than major issues, for which there is no fix.
Intermittently records scheduled programmes
We're working very closely with suppliers to resolve issues with data on some channels that sometimes causes recordings to fail - this has significantly improved over the last 2 months, but the data is still reviewed every week to identify the cause of every failure, to learn what can be improved. The aim is to get data-related failures down to zero. I don't know the cause of your specific failures, but technical support can see them all and identify if there's something that needs investigation. Your Now/Next photo suggests that your TV Guide data is corrupt, which could be a big clue.
Reboots itself for no reason
The box logs every time it reboots, and why. This can be checked by the technical support team too.
wind back stops working
This looks very likely to be related to the TV Guide issue too.
In your situation, I would recommend a full factory reset before anything else, to rebuild the TV Guide. From there, I would recommend that the power to the box isn't turned off at the mains, and see how well it performs. If it still fails frequently then additional logging can be enabled on the box to potentially identify why it's getting into a bad state,
