According to my experience, if the landlord buys things online by stages, the number of stages is the landlord's own choice. It's hard to change when it's done, and it can only be terminated early. As for the installment fee, it is inevitable, and it is still calculated according to 24 installments.

If it is a refund, you need to discuss it with the online seller. If the seller is willing, the landlord can buy it again.