Random lighting fault - Skoda Octavia MkII 1.9VRS estate

Hi people, hopefully somebody out there can help with a random lighting fault.

I have lost at least one of each light/indicator on each side front and rear? This happened about 1 month ago and after changing many bulbs and disconnecting switches/light clusters etc they suddenly came back on when moved the headlamp dimmer switch and then could not get it to happen again. The car was fine for around a month and has now happened again but intermittently with no logic at all, will come on or off while drive and/or when start ignition? My helpful local mechanic has helped me although now unsure where to go from here, we have disconnected the BCM unit and reconnected but although it did not instantly make lights work they did later come on so our next thought is to replace this unit although at £220 +vat it is not cheap. The number on the unit is BCM 1k0 937 087 D Sorry for the long description but thought I would try and get everything down, hopefully that makes sense to somebody?

Thanks in advance