Holden Vectra 2004 CDXI 3.2 hatch Air con issues

Hey Guys, I got my Holden Vectra about 4 months ago, stupid me didn't check the aircon when I bought it (it was cold back then) and now I've discovered it's not working. Holden have replaced the evaporator but still nothing. They now say it needs the Pump replaced too which is another $700+ On top of the $1600 for the evaporator.
Can anyone recommend a decent mechanic in Melbourne that won't charge me a ridiculous sum?

On another matter, I was advised I can add features like Reverse sensors but I've seen a few vectras around that have them... What's the go with this?

Thanks in advance.

@guy 27

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Sensors I can help out with. have a few options for you on the shelf here.

As for aircon. if they are replacing with a brand new ac compressor for that price its very reasonable.
although they have charged quite high for evaporator.