因为我个人失误，算错金额， 多余金额已退款。不过客户那边需要退款文件说明书：
For my records it will be helpful if you can send some kind of document for the refund.
我经验不足，这么正式的文件不会，还请大师帮忙。
Refund Statement
We have received payment $390.0 from XX on 29/July, since calculation error ,
The correct amount should be $371.0. Extra $19.0 payment will be refund on 30/July.
Refund Paypal account : xxxxxxxxxxxx
发表于 2019-7-30 10:23:00
