Drilling hardened steel

[Jackimus]

What car is it (or more correctly, what are the pedals out of)? It seems odd that the pedals aren't painted (they look like they've been blasted).

I think lack of cutting pressure is your main issue there. As said, block the pedal up so it can't move and then get plenty of pressure on it. Also don't discount that the grind on cheap drills can leave them with no clearance so they'll never cut.

2013 Alfa Romeo Mito, these are the stock pedals. When I put all the weight I could onto it was when I snapped the smaller bits. I was pushing against the hard bottom of the brakes which I thought might help by having them pushing back? But probably introduced more flex so I will try blocking them.

Looks to me somone has attacked them before and then covered it up with a thick brush of silver paint! You can see where thebpaint has flaked off..

Definitely the case, the silver has been sprayed on, it gradients further up the arm back to the stock black paint.