variation charges after soil and contour test

hi, did someone come across below situation?

we paid deposit and got the contract signed after colours and electricals. and from then waited for almost a year for the land to get released and registered. now McDonald jones is doing the soil and contour test. if the plan that i signed on does not suit on the current contour and if it requires alteration to suit the slope, will there be $1k variation charge for the alteration of plans on top of the change?

And will Mcdonald Jones build retaining walls? if so, how reasonable are they with the pricing of cut and fill and retaining walls?

Thanks in Advance

Why will you sign the build contract before your land got titled.
$1k variation sounds ok as it is a structural change after signing the contract.

No builder is reasonable in pricing AFTER signing the contract as it attracts post contract variation.