백화점에서 산 50만원짜리 세이코 쿼츠시계가 한달도 채안되서  고장이나버렷내요 시간은1분씩늦고 크 노그래프분침은 아예 멈춰서버렷고요 보증서는있고 영수증은 없어진 상태인데 환불이나 교환가능할가요?