Saw this probably in late 80s but would have been made much earlier. Parents and kids are trapped in their house by a solid grey wall or substance. They try all manner of thing to escape or to cut through it, including climbing up the chimney but can’t make a dent in it. The phone is off and there’s only a strange symbol on the TV screen. The house is getting hotter and hotter and there’s no water, and eventually they notice the strange symbol everywhere – on the front of the car, on food products. It looks a bit like the Opel logo. Eventually they’re getting so hot and have run out of liquids that they go to lie on a bed together to die. At this point the scene cuts to a dolls’ house with figures on the bed and a girl’s hand lifts the figures from the bed. Then it ends with the words onscreen to the effect ‘this story is true, it just hasn’t happened yet’.