SYDNEY, Australia - A grandmother who survived three days trapped by her overturned car after a road accident on Christmas Day became so desperate she tried to amputate her trapped and rotting leg.With her cellphone battery dying, Deborah McKnight couldn't reach emergency help after her car rolled over an embankment on an isolated country road on Sunday.'SHE'S VERY TOUGH'"She told me she tried to cut her leg off but she couldn't get through the bone," her daughter Ebony told Sydney's Daily Telegraph on Friday. "I don't know what she used. I felt sick when she told me that."She doesn't know how she survived - she said she thought of her grand kids and kids. She is very tough."McKnight had been driving near Batlow, in south-east Australia, when she swerved to avoid a kangaroo, lost control of her car and it went through a guard rail and tumbled down a cliff.The Holden Commodore landed on its roof at the foot of a tree and McKnight was trapped with her left leg partly outside the vehicle and crushed against the ground. It apparently started to rot and doctors later said the maggots that infested it probably saved her life.CHRISTMAS PRESENTSMcKnight, who is in her mid-40's, waited through the summer heat and a hailstorm, yelling to cars passing just metres away on the road above as her damaged leg worsened. She was eventually found when a teenager walking to a neighbour's property late on Wednesday afternoon heard her moans and found the wreck which was still holding childrens' Christmas presents.Police said the woman was lucky to be alive. "She was so desperate she was actually going to cut off her leg herself but she couldn't find anything sharp enough," Sergeant Brian Hammond said on Thursday.McKnight was flown to Canberra Hospital where her left leg was finally amputated above the knee.