check engine light came on -worried!!!!!

Hi guys. Just to pick up on this thread, I'll give you my story so far. Couple of months ago my "check engine" light on while I was driving home from work. My car is a 2007 VE SSV 6M ute. Had my local auto sparky check the DTC. P0420. He changed the front O2 sensor. Light came back. He changed rear O2 sensor. Light came back. Changed right side cat. Light came back. Then I contacted my local stealer and gave them the history. Bring it in they said. Called them at lunchtime and was told they can't fix it! It is a problem that Holden are aware of, and are waiting for a software fix. After being told that it is a problem that Holden are aware of, "that'll be $121 thanks". Was told to call back in a month to check on possible software upgrades To add to my chagrin, on the front door is a sign that says "Visa & Mastercard welcome". Under this sign is a locally printed notice that says "Visa & Mastercard attract 1.25% surcharge". NOT HAPPY JAN! Is this payback for not getting the car serviced at the local dealer to maintain my extended warranty? Is there an embedded code in the software that is designed to force unsuspecting punters to take the car back to the dealer so they can charge the minimum diagnostic fee? Happened last year in April when my cruise control & traction control weren't working. It needed a "software upgrade", which didn't actually fix the problem anyway-at least not straight away. That's my rant over. Any hints out there?
Cheers, Mike

Take it to a tuner in your area? Where are you located?

Wollongong-specifically, Mt Keira. Cheers, Mike