Back to back

This is a story contributed by my sister. This story happened in Taiwan and quite famous, it seems. It has many versions of itself because so many people share the same story. Two girls shared the same room and were roommates. One day, a girl lets call her A wanted to go back to village and B, being a dear and concern friend, smsed her when she was on her way back to the village. No smses were replied and her phone could not be reached. B began to worry and kept calling A to make sure she was alright. On the forth day, A's phone is finally reached but no one picked up. The last sms B sent to A was 'Where r u? Im really worried for u'. One night, when B was almost asleep, she received a sms from A and it said 'Back to back'. B was stunned and began to look around. B was on her upper part of double decker and she noticed that B' stuffs were missing. She thought she had packed most of her belongings back to village but it seems like all her stuffs were missing completely. To her horror, she saw A was tied at the back of her upper decker bed, dead. It was then known that A was killed after a robbery in the hostel room and her body was tied at the back of the upper decker bed which explains why dead A smsed to B of her whereabout which is back to back with her. This story is a bit sceptical, how can A not noticed B was tied down her bed and how A's body never rot and let out stench smell even after a few days. No matter how doubtful this story is, it remains a horror story that circulates the Taiwanese.