[talkingcars]

The heater matrix is actually behind the central consol at the bottom of the heater box.

I have no experience of a factory fit sun roof on the ZS but most cars have a pipe at each corner that run down the A and C pillers and empty in to the wheel well. It could be that if the car was parked leaning to the drivers corner that this drain wasn't draining properly so rain water was finding it's way to this corner instead of going down the drain.

The easiest way to clear the drain hoses is to blast compressed air down them.