Thanks to edlee and gas man for your recomendations, to edlee first, its not plaster board sorry if i gave that impresion it is an old wall and is made up of a mix of plaster cotton waste,string and...
I am puting up a new hand rail in the house but the hole in the plaster wall are now to big to take a new rawl plug but the problem is that the space between the plaster and the wall is not the same...