I found that removing the 3 bolts that hold the plastic frame to the metal work means you don't have to cut anything or excessively bend the plastic out of the way. I've put together this 5 min YouTube clip which describes it in a bit more detail. The whole job of removing the aux heater took me about 40 mins with no swearing or cut hands.

How to remove an auxiliary heater - easy way (VW, Audi, Skoda, Seat) - YouTube

Any questions, let me know.