多退少补的英文：
refund for any overpayment or a supplemental payment for any deficiency

参考例句：

To return the overcharge and demand payment of the shortage
多退少补

refund是什么意思：
n. 归还，偿还额，退款
v. 归还，退还；退款，偿付

Refunds We regret we are unable to unthorise refunds without a receipt.
退款请凭发票办理退款手续。

You may exchange the shirt but not return it for a refund.
你可调换这件衬衫，但不能退货。

Guarantee change of article or refund if unsatisfactory.
包退包换。

overpayment是什么意思：
超额偿付; 超付

Overpayment of a tax is refundable at the end of the year.
多付出的税金年底可以偿还。

But the risk of overpayment in a secondary buy-out is great.
但是二次收购超额支付的风险很大。

supplemental是什么意思：
adj. 补充的

This is a Sunday supplement.
这是一份星期日增刊。

The diet supplement is important for me.
饮食补给品对我很重要。

a 10 supplement for a single room with a shower
带淋浴间的单人房间需付10英镑附加费.