Solid wall with plaster on top

[Idiyh]

Hey guys,
I have removed toilet cistern from the solid wall that was plastered over in the bathroom.. I have removed the old rusted screws... This has left a 2 in deep hole and some bigger 2 inch width superficial damage of the surface plaster... How can I repair the hole so it's as strong a wall as before the holes were drilled? ... I presume Polly filla is just soft and powdery and weak to drill holes back into and it will just disintegrate... I have to used the same location but it needs to be strong like the holes are being drilled for the first time if that makes sense.

 

[Dad'n'lad]

If you're careful you could drill new holes in the cistern, or just one in the centre. Bit of silicon or other grabbing agent ( if you want to ), and you're done.