Hora, before you reach for the wallet, spend some time looking after your brakes.
If you're on here saying they're cr@p, but you havent bled them etc etc then go away, clean them bleed them, bleed them again, sand the discs and pads, clean the rotors and bed them in again.
Everything needs a degree of maintenance.
Oh and before you clean them, drop some mineral oil around the pistons, gently pull the lever to get them out, wipe around the pistons, push them back in and repeat about 5 times for each piston.
Shimano brakes are lower maintenance than say juicys, but they still need looking after.
If they are still as rubbish after the above i'll be very surprised.