Wall behind boiler- bad job by plumber

[Saya]

I got a new boiler fitted. The plumber, however left the wall behind stripped down to bricks, pieces of old plaster.
The issue is - there are dust particles falling off the wall and spreading all over my kitchen with boiler use.

The solution I imagine would be to plaster behind the boiler pipes somehow. But this is hard because of lack of space.
But a handyman suggest using - Soudal genius gap filling expanding foam https://www.toolstation.com/soudal-genius-gun-gap-filling-expanding-foam/p15361

Is this a good idea?

 

[RandomGrinch]

Is there any chance of posting a picture, to give us an idea of the problem?
It might be impossible to plaster behind the boiler pipes, but it may be possible to slip a piece of plasterboard behind there?
This could be attached by foam, and may be what the handyman meant?

 

[Saya]

Thanks for replying @RandomGrinch
I have attached some pictures. He said he can spray the foam and then it will dry and he can cut it into shape….

 

[Stuckinarut]

I wouldn’t use expanding foam. Could possibly use bond and skim, or perhaps if you’ve some tiles left then tile it?

 

[foxhole]

Did the Plumber cause the damage or was already there? Looks like it might have ibeen in poor condition before the boiler was fitted.
Do you intend to hide the boiler?