Do they have a built shed of that model in the store?
I don’t see why at all they would owe you a larger shed and a foundation at no cost. It’s ultimately up to you to make sure it fits your needs.
If the OP bought the shed in good faith with Home Depot’s assurance that the door was a certain size, and the door actually was not that size, that’s on Home Depot. I would have checked myself beforehand just to be sure, but that doesn’t change the fact that somebody at Home Depot sold the shed under false pretenses.
No built model at the store or we would have verified the dimensions. I don’t think they owe us a bigger shed, but when they started giving me a hassle I felt I needed some negotiating room. They are specifically telling me that the shed must be returned in condition that is sellable, and of course when taking apart an item that isn’t meant to be taken apart, you can’t guarantee that. With the statement from them that it must be in that condition upon return I am concerned that if we try to take it apart and it does break we won’t get our money back, nor will we have a shed that we could use for something else or sell to someone that could use it.