Holden recalled all 2009-2010 Barinas because of a sticky valve in the Electronic Brake Control Module. If affected by the problem the braking performance was reduced and the pedal feel was spongy. That would seem to be the most likely cause of your problem. Take it to a Holden dealer and have it checked.

You certainly shouldn't need to recondition the cylinder head after such a short time. I would be checking for reasons the valves might be sticking. As the fuel injectors gave trouble shortly afterwards I would be looking to the fuel side of the engine. First, I would change fuel brands, definitely not use E10, perhaps use a higher-octane fuel, and regularly run fuel system cleaner through the car.

I would expect that the issues relating to the air-conditioner and airbags would be covered by the warranty, if you are told that it isn't then kick up a stick. Contact Holden Customer Service on 1800 033 349.