You need to make sure the rear shoes (if equipped with drum brakes) is adjusted up, as rear adjust controls pedal feel/height. If the shoes have to reach out to apply friction, your pedal is going down with it.
Also verify the pads at front are equal in thickness, and that the calipers are FREE on the slides, this will ruin one's attempt to get a good brake pedal.
If rear wheel disc, verify calipers/slides all move freely.
Next step is to bleed the entire system, and since the car is 3yr old, change the brake fluid...... ALL NEW-CLEAN fluid... DOT 3 will hold moisture over time, it's supposed to, do not want water in the hydraulic system, clean fluid will prevent the chance of ABS pump/valve corrosion over time.
If all the above does not remedy, the master cylider is last part to be condemed.