Useless and unopened are two concepts. If it is unopened and it is on the day of purchase or the next day, it can usually be returned, but it will not work after a long time. Moreover, there is no problem of bullying customers in this store: people return this thing unconditionally without promising that it is cheaper than it is sold in other places. If you find something cheap in other places and want to return it, people will not return it, which is completely in line with the regulations. Giving you a refund is taking care of you