Removing Shower Diverter Seat

I attempted to remove a square drive diverter seat with a stepped
seat removal tool and the end broke off inside the seat.

I thought I had inserted it up to the correct size (one size too small) and twisted it off.

The end of the removal tool is stuck inside the seat.

Any ideas on how to remove? I tried drilling but the metal appears
to hard. Maybe a special drill bit?

Thanks in advance.

At this point you may want to ask if she liked the valve to begin with and if she would like a new one.

tool

It is too late now, but you should have bought the $1.00 removal tool instead of the $.25 one and it would not have broken off, unless you used a 5' lever trying to twist it. Unless you can loosen it in the seat by wiggling it with a probe of some kind and then extract it with a small magnet, you are probably out of luck.