回复：What is the pressure reading when they stopped pressing down?

You are right that the contract should be based on the engineering report and contract.  Any other auguments (landlord/contracto/sub contractor)  are really meaningless.
I doubt four micro piles could jack up the house and close up the crack.  
It may stop the crack getting bigger at best,
I guess you could try to pay less since the subcontractor(I guess) changed the scope (change the location of the piles) of work.