Pay the upgrade fee for the better approach that you turned down. They told you what you'd be getting, and you agreed to it. Buyer's remorse at this stage doesn't mean anyone owes you anything.

Hi Sophie,

This is not buyers remorse. As I said, I am completely okay with having a multiple piece tread to save the money. However, I don't want to have a safety hazard. It was never mention the tread would be raised.

It would be up to the building inspector to determine if this is a safety hazard or not. I believe you will find that these add-on bullnoses are permitted providing they do not exceed a certain height above the treads top surface.

Graham

The only thing a builder understands is that you're not going to close until this is resolved to your satisfaction. Be reasonable and willing to pay more and he'll see the light. A written promise to fix it after closing is worthless.

Quick way to get a lien slapped on the house before you even buy it if you try not paying. Those types of stairs pass code, and pass inspection, even though they are less than optimal. 3/8". That's the magic number. You have no standing to withhold any payment based on you changing your mind.