在ebay上收到买家如此答复，我该取消订单并退款吗？

今天一早收到客户的信息：
Hello!
We ordered and paid for this last night. We accepted your counteroffer too quickly, and it's unfair for $27 even with free shipping. We found another one that is up for $17 with $3 to ship it. We were going to cancel our order, but we chose to write to you instead and if you reconsider our offer for $24, we'll keep our deal. If you decline this, we'll cancel this order and buy it from the other seller tomorrow. Thanks for your time. We'd rather not cancel it from you, because we want to keep our deal with you for $24. We'd prefer if you stuck to our first deal. It is Sunday and it is almost 1 PM here. Please reply to us as soon as possible. Thanks again.
大致意思如下：
这款产品$27包邮还是太贵了，我昨晚确认的太快。后面又找了一家包邮$20的，所以想跟你取消订单。但如果你能接受$24的价格，我们可以重新考虑在你这边下单。请尽快答复。
交易都结束了，我已无心再跟他们讨价还价，因为订单生成，款都付了，所以他们要如何变更价格呢？不想收到客人的差评啊，该怎么做才对呢？