Help Please!! Air Con issue
 

Hello all, My first post here. I have a 2009 Holden/Chevy Cruze CDX model here in Australia. I have the car for 2 years and never had any real dramas. From last few days, air con has started to play up. My car is right hand drive. 2 x Passenger side vents are stuck on cold regardless if I turn temperature dial towards hot or cold. 2 x Driver side vents show change in temperature however don't go extreme cold or extreme hot. I thought this could be due to faulty Blend Door actuator. I removed it and found it to be working perfectly. All other actuators (mode and air control) are also working perfectly. I think it could be broken blend door flap. I have no idea how to replace it. I have never taken the dash out so not really sure. The dealer is asking $125 for scan and $100/hour labour which will cost me at least $1500. Any ideas what can be done? Is there anything else that I can try before?