Advice on Rectification of missing acoustic insulation please?

[Leigha]

We have just found out that our builders have failed to install the 25mm glass mineral wool acoustic insulation shown in the plans for our interior walls on our new build.  They have agreed it is missing and have offered to rectify it by cutting large holes in the walls and feeding the insulation in (it comes on rolls) then repairing the holes with plasterboard/battens and re-plastering and re-painting.

The question we have is - should we accept this proposed method of rectification? 
Does anyone have any experience of this?  We are wondering how they can ensure that all the areas are properly covered using this method - particularly areas where there are cables, pipes, power sockets, light switches etc.   Call me a cynic but having already been given suspect information regarding other snags and the method of rectification we are finding it difficult to believe anything we are told by them!

We are wondering if this method is acceptable or should they be taking the plasterboard off the walls and starting again?

Thanks in advance for any advice anyone can offer

Leigh

[New Home Expert]

You are right to be concerned. Who is the housebuilder?

It would be nigh on impossible to add acoustic insulation to a stud internal wall properly by cutting letterbox holes and stuffing it in.

Quite frankly the amount of work involved in both this and the extensive making good of your then "advent calendar" wall, it would be easier and cheaper to take one side of the wall down add the insulation properly and re fix and joint the board and re decorate.