Residents in three blocks of flats in Battersea in south London spent Christmas Day without electricity or heating after a power cut.
The 51 flats had their power cut on Friday night. Power supply was restored to the last 40 flats on Sunday night.
Tenant Haja Tucker said she and her three children ate boiled plantain for Christmas while neighbour Dorothy Kasonde said she was wrapped in duvets.
UK Power Networks said an underground cable fault had caused the problem.
The company said work to restore the supply had been delayed due to a burst water main.
Residents of the buildings on Haydon Way were also left without water for about three hours on Sunday morning due to the burst main.
Thames Water said the problem was caused when contractors working on behalf of the power company damaged a water main on St John's Hill on Saturday. The firm said it was informed about the problem on Sunday.
Ms Tucker said her children had been looking forward to a busy day at home with friends invited to Christmas lunch, but those plans had to be cancelled.
She said: "Even though our hob is gas, our grill and oven are electric. So we boiled some plantain for dinner.
"We are cold, [we are wearing] double jumpers and socks. It's very sad.
"Last night the kids went to bed at 7pm, it's dampened them, they were looking forward to Christmas."
Ms Kasonde, 39, said: "I lived on cold milk and cereal the whole day (on Saturday).
"I have four duvets and layers on me and I am sitting in a chair in the bathroom because the bedroom is frozen."
A spokeswoman from Viridian Housing Association, which owns the blocks, blamed the power company and Thames Water for what she described as "this major problem".
She said she had tried to contact the electricity company "10 times today".
"If something doesn't happen I'm going to ask the housing association to take some action," she added.
UK Power Networks said: "Power was interrupted to 51 customers at about 10.30pm on Christmas Eve and our engineers worked through the night to repair the fault, restoring power to 11 customers by about 2.45am on Christmas Day.
"Unfortunately while we were working to locate and fix the fault a water main burst which has prevented our teams from carrying out the work until the leak was fixed.
"We realise how difficult it is to be without power, particularly over the Christmas holiday and apologise to our customers for any inconvenience."
Volunteers from British Red Cross were checking on vulnerable residents, she added.
Electricity supply was restored to the buildings after 2200 GMT, the company said.