Gave the model, details, where's the fun in that.?
Had you posted " got lanruvver wiv bubbles growing out of dat wot is it then you bunk of ****ers" we might have treated you differently.
Mine are square section all the way down. Slightly tapered for the last third of their length & have kind of bladed edges that bite into the 'ole. There in the shed so I'm farked if I'm getting them out now to take a piccie.
I'm guessing the shaft is round? If it weren't it probably will be now! Even two pairs of moles grips might do it. One sticking out each side to act like handles.
The bolt extractors I use are square section so you can get a spanner on 'em. They're tapped (well, hammered in) and are as strong...
Turn it using a hand tool/breaker bar type set up. Whacking the drill on might help shock it out, but since it ain't I think you need some carefully applied leverage.