How much to pay a decorator to patch up crumbly walls and put up wall paper?

[janji]

Old house with a few dents in old walls (mainly caused by trying to remove 3 or more layers of welded on paper)! How much have you /do you pay a decorator to patch up and paper an average sized living room?

Dont know if this helps. We paid 700 for front room to be wallpapered and our staircase is in our front room so he carried on all the way up and did our stairs and small landing ( quite big drops of paper on our stairs) also he painted staircase skirtings in front room on landing and down the stairs also painted 3 windows (we have old sash windows) quite big windows. Also for that he papered our bedroom and painted ceiling. We did the sanding of woodwork to keep price down.