Given a damaged fridge twice, food stuff rotten

I'm writing on behalf of my sister who does not have access to the internet. She bought a defy fridge cash on the 21 November 2015. She received a fridge that would not get cool this being said she had nothing to keep her food items in so the fridge was quite urgent. They then bought her a so called new fridge days later, by this time her child's school cold meats had already gone off as well as the milk. This fridge also doesn't work properly so even more of her food items went off. She is still waiting for the fridge to be replaced. She was told that it should happen by Wednesday. This is unacceptable as it is 10 days since she paid cash for it and 10 days being without a proper working fridge with perishables getting rotten by the day. Please call her urgently to sort this out on ***