It is a 60’s/70’s movie??
Think it may have been black and white not sure?
Family living in a 2 story house. It’s encased with only a few metres around the house with steel walls with no way out.
The people in the house discover that everything in the house have a symbol (trademark) on everything in the house. Including themselves.
The house is getting hotter and hotter as they try to find a way out.
At the end of the movie you discover that the house and contents are a doll house and its dolls. That has been put into a heating vent via a cruel older brother of a little girl.