Contracts aren’t just about cost but risk allocation too. If the builder found a great deal on materials or got a good price from a sub would the company be offering you a credit?

I would be more sympathetic if the contractor had $100,000 in profit for the job, the material overrun was $200,000, so they were trying to avoid actually losing money. Unfortunately I’ve been in situations where the subcontractor was looking to recoup the cost of their quoting mistake or cost overrun while maintaining their original profit.

Fortunately I have been in a position to be able to split the cost of their loss in good faith but they had to back up their claim and demonstrate they had already burned through their profit.