Cooking pads (which you have certainly done) affects them in different ways, some melt onto the discs, some turn to coal and break up. The key is to try and work out what operating range your stoppers have and then buy a pad to suit... Or, get some cooling sorted.
That Clio 200 I had only had 4 pot Brembos and 312s, and the would stop all day on track. I'm guessing your car is lighter too? You've got the hardware, you just have to make them work right.
There's temp paint or see if someone will lend you an infra red temp gauge for a day.
Personally with how cheap solid discs are these days, I'd get some aggressive pads and let them eat as many discs as they like - rather than then ruin pads or have sh*t performance.
I've used Carbotech, PF, Pagid and Carbon Lorraine. Non are cheap, but if you want to play - you've gotta pay!