Hi shaking, I would score the walls quite well. Then put a small amount of Washing up liquid in some warm water and apply this to the walls with a brush, do this a couple of times before you start trying to get the paper off. The washing up liquid will stop the paper drying out too quickly which will help loosen it. One thought, have the walls got plaster on them. Sometimes to cut costs walls have often been papered over bare plasterboard and then getting the paper off is a very hard job.