Hi,
sorry to hear this. I'll try to address these points as best I can.
With regard to the recordings over christmas etc, not much I can do about that retrospectively.
When the TV is switched off, turning it back on may start up on a default channel. Some TV's can have a default channel set as startup, so always a good idea to look through the TV settings menus to see if this is the case. Some may autoselect a specific HDMI port etc, and this can often be down to the TV itself, so can be beyond our control.
With regard to volume, the youview box is usually set at 50% volume level by default, so I do recommend you increase this via the remote to 100%. Please note however, if you have set the remote to control the volume level of the TV, you may have to reset the remote to control the box. If you do, Press 1 & 6 together for 3 seconds – Red LED turns on. Enter code : 9 8 1 Red light will blink and remote will be set to Factory Settings.