Just Stop Oil activists tucked themselves into a Harrods display bed as part of fuel poverty protests sweeping the UK.
Footage of so-called "warm up" demonstrations on Saturday also showed security guards confronting protesters lying on sofas inside the shop in Knightsbridge, London.
The eco-activists want action over "sky-rocketing" energy bills and were joined by other grassroots movements, including Don't Pay UK and Fuel Poverty Action.
They said they were "rapidly" escorted out of the department store by about 20 security guards.
Protests were held across the country, including at the British Museum and Scottish Power's HQ as part of a national day of action on fuel poverty, organisers said.
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Don't Pay said campaigners bedded down with blankets, sleeping bags and hot water bottles in the foyer of Glasgow-based Scottish Power at about 9am.
Another "warm up" saw activists enter the British Museum's great hall - the largest indoor public square in Europe - where they also protested against the Bloomsbury venue's sponsorship links with oil giant BP, Don't Pay said.
Footage showed visitors in the background as campaigners sat in a circle on the floor.
A third group entered the Westfield shopping centre in Stratford, east London.
Protesters waved signs reading "Heat or eat Rishi" and "End fuel poverty now".
"Warm up" protests involve "occupying a location to run an unauthorised warm bank and bring attention to sky-rocketing rates of fuel poverty", Don't Pay said.
In Hastings, campaigners were due to enter a Barclays branch due to the bank's investments in fossil fuels, which campaigners say exacerbate energy prices and the climate crisis.
Other warm up protests were set for a shopping centre in Manchester, and in Liverpool, Brighton and Bristol.
A Just Stop Oil spokesman said: "This government is allowing ordinary people to starve and freeze this winter as greedy energy companies squeeze every last penny out of us. The health service is in crisis, workers' wages are being squeezed and nurses are using food banks.
"Austerity is a political choice and the cost-of-living crisis is an unprovoked attack on ordinary people.
"Worse still, rocketing energy prices are funding the companies who are torching the climate. Rishi Sunak's government plans to allow over 100 new UK fossil fuel projects. They are signing our death warrants.
"New oil and gas is criminal, an act of genocide against billions of people in the poorest countries on Earth and an act of war against the young."
Neil Smith from Don't Pay added: "No one should go cold in winter, yet what we're seeing is a mass default on these extortionate energy bills and thousands set to freeze in their homes.
"While the Government stands by, we're coming together in our communities to fight back and keep each other warm."
Don't Pay has called on people to cancel direct debits for their energy bills in response to the "mass default" among those who cannot afford to heat their homes.
The groups want the Government to immediately tackle the energy and cost-of-living crisis by introducing Energy For All, defined as "a universal, free band of energy to cover people's necessities".
This would be paid for by "ending all public money subsidising fossil fuels, a more effective windfall tax on energy companies and higher tariffs on luxury household energy use".
Stuart Bretherton, Fuel Poverty Action co-ordinator, said: "Energy For All would achieve what our energy system and economy should ultimately be geared towards - ensuring everyone's basic needs are met.
"Ordinary people cannot keep footing the bill for crises created by the wealthy; it's time for the big polluters and profiteers to pay their share.
"Through this we could also incentivise much needed climate action on home insulation and a transition to renewables."
