Getting charged double the quote

so following the story that happened in here :
https://www.ozbargain.com.au/node/180965

I took car to the mechanic at fineline automotive, I spoke the one of the guy named Anthony and by the end of yesterday, he told me that the welding cost is $120 + 2 hours labour cost etc2, he said the final figure is $400, which i happily accepted because its less than what I paid before with another mechanic which is $500 (told him this)

Today, a lady from fineline call me and told me the car is ready to be picked up and said that the total cost is $685, i was shocked and asked how come its different than what was quote yesterday, and she said, the welding cost is $150 and it takes almost 4 hours labour cost etc2. I told her that's totally different than what Anthony told me, so I insisted to speak to Anthony, however she said that Anthony is out so I can't talk to him at the moment.

Half an hour later, I got a call from Anthony and he apologize that he underestimate the cost etc2 and asked me how much it cost me to fixed it at another place before in which i told him and he said, he will accept that amount.

I wish I had a record of the conversation that happened yesterday so I can prove it but I don't
I don't know what else I can do in this situation.
Is there any other good mechanic out there in NSW who is not trying to rip you off.