buy better equipment
If you don't want to lose your PVR schedules or have to retune when this kind of thing happens, buy some better equipment. A decent freeview PVR should be able to background scan the currently tuned multiplexes finding new channels and moving around the old ones without any kind of manual retune. Retuning should only be required when the multiplexes switch frequencies.
A decent PVR should also be able to maintain series links and scheduled recordings using something better than the EPG number.