I submitted a bid for cleaning that covered just the one time construction clean. The subcontract asked for an additional 5k allowance and we missed it on our estimate. We did the work and negotiated an additional 1k for more cleaning they asked for (at the time didn’t know about the 5k allowance) I submitted our invoice and now they are taking off 4K from our original bid. They said we are tied to the contract we signed but not the estimate we submitted that didn’t include an “additional allowance”. They basically took our price for cleaning and broke it up into base cleaning price and extra 5k allowance. Is this ethical?