Dropouts / Reboots

[#1]

I know there's plenty of discussions on here about frequent router dropouts and reboots but I'm struggling to find a solution that works for me.
My Hub One reboots itself daily between 8 and 9 pm and around 11am (when no one's home).
My wife experienced terrible connection problems when trying to work off Google Drive as well. And my speeds have been up and down like a yoyo, rarely hitting the 30 mps I'm paying for.
I've had a ticket open for six weeks on this and was supposed to get an engineer visit today which never arrived, so to say I'm ****ed off at the moment is an understatement.
I'm not an idiot but I'm not a tech whizz either, so if anyone has any ideas I'd be grateful. Obviously I've tried all the standard troubleshooting and PN assure me the line is fine.

As a side note, would this issue going unresolved much longer mean I could leave PN?

[#2]

Sorry to hear this.

We're investigating this further and we'll update the open ticket on your account as soon as we know more

[#3]

Thanks for the reply but I'm not sure what else to do. I informed previously I could only have an engineer on Mondays. I was told one would come round, then was told I couldn't have an appointment on Mondays!
Looking round the forums this is a hugely common problem which an engineer visit will not resolve, and seems to only be fixed by changing to a different model router which I'm not prepared to shell out for. So we're a bit stuck. The Hub One seems to be incapable of dealing with the fibre use but nothing is being done about it.