Idiot alert - drilled pre cast flue

[Richo106]

As you can tell by the title I have been stupid and drilled the pre cast flue for my gas fire. I am building a fake chimney breast and in my haste to put up the frame work I fixed 2 batons using plugs and screws into my class 2 pre cast flue. The holes will be hidden in the new breast anyway but what is the best way to repair this?
The wall is dot and dabbed plasterboard so i can open the plasterboard to get to the holes.

Thanks