我新建了一个20元-2元的单品券，支付时支付了30元 优惠券抵扣2元 实际支付28元

支付时返回字段 {"promotion_detail":[{"promotion_id":"16469835612","name":"满20—2 月租测试","scope":"SINGLE","type":"DISCOUNT","amount":200,"activity_id":"15184344","wxpay_contribute":0,"merchant_contribute":200,"other_contribute":0,"goods_detail":[{"goods_id":"ebike_sku_month_parking_20","quantity":6,"price":3000,"discount_amount":200}]}]}

单品退款时，我申请的是部分退款，申请字段{"detail":{"goods_detail":[{"price":500,"goods_id":"ebike_sku_month_parking_20","refund_amount":500,"refund_quantity":1}]}}

是因为退款时 优惠单品 单价输入错误吗？