I'm getting two stories on the subject of changing the heater matrix. Some people say it's like a Golf and you have to have the whole dashboard and half the interior out. Others (mostly with LHD cars) say you just need to take the trim panels in the passenger footwell out and be a bit dexterous. 

 

Anyone got any hands on experience of doing one of these?

You only need to remove the ashtray, passenger footwell carpet upright and glovebox to get access.

 

There are a few bits and bobs to disconnect along the way but nothing difficult, there are videos on the tube.

 

30 minutes should see you to the matrix.