Isolation valve help

[Nian]

Hi all

I'd really appreciate some help!

Had plumbers in to redo our bathroom & it all looks great. Only problem is they have left the mains isolation valve screw slot stripped (see image).

I've tried carefully to rotate it but the screw is pretty stiff and I could tell I was just making it worse, so gave up for fear of not being able to turn it back.

I see there is a threaded hole in the centre of the screw, is there an alternative tool I can use, or does the whole valve need to be replaced?

Any replies much appreciated.

Thanks, Stephen

 

[He who knows]

If they broke it get them back to fix it at their expense.