Electrical - locking and buzzers

Hello Ladies and Gents,

I am after a little bit of diagnostic advice:

My Octavia Mk1 RS has a few issues. When I open the drives door it does not turn on the interior light or buz to tell me I have left my lights on. The central locking also does not consistently open the two rear doors. Sometimes it opens both, sometimes 1, sometimes neither. This is the case when either using the remote or the switch on the drivers door.

Any advice would be greatly appreciated, especially with part numbers.

Thank you.

Jim