How to make good a rubbish paint job.

I could do with some more clarification on the subject, were the walls originally papered - which you wanted removing to paint? Or lining paper applied then painted? Either way the person you hired was obviously not qualified to do the job asked of him. How he could make a mess of such a simple job I have no idea, my answer would be to hire someone who has pride in their work as what you are describing is someone who obviously has no clue how to decorate, preparation is key to a quality job and not picking up on any of these while working is troubling to say the least. You as the client know what quality you want, I would hire another Decorator and ask him his opinion on the previous work, he will probably pick up on the faults straight away and tell you the remedy, quality is key and getting that is all about preparation. It's either that or try a bit of DIY yourself!

If the walls are so damaged or pitted after removing the wallpaper that filling each individual hole with joint compound isn't practical, skim coat the wall instead. Allow the compound to dry. Then grab a pole sander and give the wall a good sanding, hitting all the high spots. Wipe down with wet cloths to get rid of the dust. Now your walls are uniform and smooth and ready for a fresh coat of paint.

Can help with it, need preparing all walls again and repaint. Main is good preparing

Any imperfections that were not clarified prior to lining are now trapped. Do not pay the decorator if you haven’t done so. Strip off and re-line for perfection. Even if you were to bash the dents and fill etc you will never have an even texture due to the nature of the surface from the lining paper being different to filler.