So sorry your project is having these stumbling blocks.
A friend had a pool built and the wall they quoted was for a certain S.F. of rock face. And the contract was either silent or said, something like it subject to change, in the details. Well it did change just like yours. It ended up needing to be twice as big to do the job.
They were quite displeased, but contractually, they were signing for a product (S.F. of surface area), not a product which had been verified (or guaranteed) to be what was needed in the end. The PB really just considered it to be like a flooring allowance when you build a new house. We'll put in a $5K, which is what you see and may disregard the overage potential, when in reality, it may end up being $10-15K or more. This is has the effect of simplifying the contract stage AND usually underestimating the final contract cost.