SONY M4 AQUA

I BOUGHT A CELLPHONE ON THE 24/03/2016 AT MENLYN TRUWORTH BRANCH.FOUR DAYS LATER ON THE 28/03/2016 THE PHONE STARTED TO FREEZ, AND I WENT BACK TO THE BRANCH.AFTER I TOOK IT TO THE BRANCH THEY PUT IT ON THE CHARGER AND IT STARTED WORKING.SO THEY SAID I CAN TAKE IT HOME WITH ME AS THEY DONT SEE ANY FAULT WITH IT.WHEN I GOT HOME LETS AFTER COUPLE OF HOURS IT FROOZE AGAIN.MEANING I HAD TO TAKE BACK TO THE STORE AND THEY TOLD ME IT HAS TO GO FOR A REPAIR.I CALLED THEM TODAY TO CHECK WITH THEM HOW ARE THEY WITH THE REPAIR.TO MY SURPRISE I WAS TOLD THAT MTN DECLINE TO FIX OR REPLACE THE PHONE.THATS MEANS I HAVE TO TAKE A PHONE THAT IS NOT WORKING AND I STILL HAVE TO PAY FOR IT.HOW FAIR ISTHAT.WHAT MAKES ME SO ANGRY THEY COULDN\T GIVE ME A REASON WHY.SOMEBODY,ANYBODY PLEASE HELP BEFORE I GO AND OPEN A CASE."