The job done so far is bad

Before getting someone else u better talk to that one who did r job first to come and fix it cause he haven’t done proper job

Talk to the person doing the job about your concerns first.

It is true that you should talk to whoever has done the work. But, frankly I would agree with you if you were to say that you have lost all faith in them being able to do the job properly if given another chance, and waste another load of wallpaper. I'd bank on saying that not only do they seem to lack decorating skills, they also have no interest in doing the necessary preperation work that wallpapering requires

Speak to the person who’s done the job in the first place but let’s be right if he’s made that much of a mess in the 1st place you don’t want him to try and put that right , speak to him politely & tell him he’s no longer required down to poor workmanship , point out all what you’ve seen , hear him and & tell him goodbye , no excuse for poor workmanship regardless of what excuses he comes up with .

Agree with all answers.but not down to a painter to take radiator off.you should have got a plumber to do that unless it wasn't plumbed in

Sounds like the said decorator has not prepared the walls right , if they are new plaster walls they need sealing with wallpaper paste. The bubbles are either from poor slinging or the from when the paper was pasted and not allowed to soak. As for the radiator, it's not usually down to the decorator to take it off but make a neat job if not. If I were you I would get a professional decorator....paper hanging is a skilled job not just putting it on and preparing walls it has to be pasted correctly and is one the first jobs an apprentice decorator learns.