DEAD BATTERY AFTER 6MONTHS

BOIGHT A RENAULT KWID 2018 MODEL, 6MONTHS LATER I HAVE DEAD BATTERY. TOOK IT FOR SERVICE AND ASKED THEM TO CHECK THE PROBLEM WITH THE BATTERY, TURNS OUT ITS DEAD, HEY PROMISED A NEW BATTERY, WEEK LATER DONT HAVE A BATTERY, NO EXPLANATION, NOTHING. IM JUST BEING TAKE FROM PILLAR TO POST AND M SO ANGRY