Legally speaking, they can ask for a full refund because their behavior has constituted a serious breach of contract. It is suggested that they call the consumer hotline to complain about them first, and then call the industrial and commercial bureau to reflect the situation. If it really doesn't work, give them a good publicity at the door of his shop, and don't think about how they treat consumers when they go to court. There is no judgment for a year or so, and the price is very high.