Ignition coil loose

one of my ignition coils is loose because the hole that’s used for the bolt to keep it secure has stripped.

I’ve had an engineer at work look at it and he said the hole is completely smooth. He said we’ve nothing at work that would be able to sort it.
Has anyone had this happen before and what’s the best way to fix it?

The car is running fine, it just sounds different. Like you can hear what’s going on inside the cylinder.
Not a big problem really but for the first time in a while I’ve no other issues with the car, apart from this.

 

Sorted. He said he thought smallest we had was 10mm. Really appreciate your help.