Engineers report

Today I have received my engineers report for a new build in Adelaide. I don't like it. The builder is charging me an extra amount (some of it for something they cannot tell me, except that it's above standard footings and some for rock which they might find and might not find and then they will credit it back).
I'm looking at some options here.
1. Agree to everything and continue (but they are telling me that I can pay more for rock if it comes out). I wonder what kind of engineers they have if they cannot be sure.
2. Drop out of the contract. It's a house and land package. I'll loose the same on deposit + stamp duty on the land which I already had bought because they insisted on it).
3. Order my own independent engineers report and see what it comes to. (I wonder how much will it cost).
I'm a builder myself but from overseas. If I was overseas I would have done the 3 option and then came to some conclusions. But since I'm here, I'm kinda lost. They are telling me that my footings are above standard but don't want to show me what their standards are. They are telling me that they found rock 2,3 meters deep. but don't know where it is exactly and they don't know how will it affect the footings which are 0,5 meters deep. The house is a custom design, because the block couldn/t fit any of their ordinary designs.
If I was telling clients the same stuff overseas, I would be out of business in no time, but here it seems to be standard practice.
Need some advice please.
Thank you for your time.

What does your Geotech report say ?
How many bore holes were drilled,etc,
Soil classification, profile and bearing capcity?
Is there other alternatives for the engineering that could have been achieved through design changes
that may have saved you money?
Blah,Blah,blah
I would be more inclined to believe an engineer before I trust the salesman/builder?
The site works excavation amount is a provisional sum, it is there for unforeseen circumstances, and the builders doesn't have to provide any expenditure justifications, he just has to provide his invoice for you to pay. If you aren't happy with that then don't proceed and you will loose your deposit...
Builders do enough free work, ie sketches, site visits,budget quotes, etc, for clients and then require a deposit in order to proceed to the preparation of plans & contract documents which costs money
....go figure "why engineering is left to last" let me say it's convenient for designers and builders

Clients have to realize on difficult sites,it would be prudent to get your own independent engineering advice and agreed to it first hand with the builder..
BTW. Its too late now

Thanks Structural. I'll go there in a few days and see how many holes were drilled (if any).
Why do you mean it's too late?
I might not proceed and buy somewhere else.

If you pull out you may loose your deposit, copyright and time spent.
If you proceed the builder will claw back more of his profit with engineering,unforeseen costs and client variations increases.
The builder is in a win-win situation

Could you do price comparisons with your neighbors? Where in Adelaide are you looking at building? We're building in S.A too

I don't think so. If I'll walk away, the builder will have to sell the land (which I own now) to someone else and it's a headache. You are right the builder might try to claw back some more. I'm thinking of canceling. Thanks.

I have asked 1 neighbor and he said that his footings were just a few hundred bucks more (he had the same builder), but his house is ordinary (standard builders design with a few changes) and a lot smaller than mine.

The funny thing is that it all finished pretty good. After the build was completed I have even received 5,5 k credit from the builder for the footings. You never know the outcome until you go through it.