I have very recently had the rear disc brakes.

Check to see if your parking brake may be apartially applied, it may have inadvertenly pushed on the pedal to make the light go on. There could also be air in the system and may need to be bled. We don't have that car in u.S so is harder for us to dagnose as we don't know if it's got abs or not so this answer is generalized. If it does have abs a code should pop up for it if an abs scanner was used.

Well if it's an automatic hand brake and there is a fuse for it then i'd check to see if a fuse blew or a relay bad. I would think that would be the area to check as it may be applying a little if it had a stuck cable it would do the same like going on but not coming off all the time. Something like that i'd really have to look at to see it to give a better diagnosis. This cold still be a hydraulic isssue as well. Where ever your brakelight warning swith is normally on proportioning valve but cold be on abs if just he back brakes were bled thenit may need a front brake bleeding as well to recenter the switch. But not being familiar with your vehicle as we don't have them here this is still another generic type answer. Good luck