Never done it so dont belive me :D. Looks like you need to slack the screw in the valeo unit or release it totally. to give you that little extra space. J

Replacing my leaky heater matrix with a Nissens Audi one, but am (literally) stuck removing the old matrix. Not wishing to take out the dash, I have cut away the supporting frame as per PaulP38's instructions. All looks OK to slide out the old...