Selling item less than amount bid

I sold an item but before posting I noticed it had damage when I said it was in good condition. The buyer still wants it and we’ve agreed to 50% off.

How do I resend invoice with the reduction?

thanks

If it’s more than you can put in postage discount, you’ll have to cancel the sale, and do a special listing for the same buyer with the new price 

You say "before sending" which would indicate they have already paid? In that case just refund the difference.

Seems to me there is a problem here.

 

It has been sold with the description given in the sold listing - the buyer could open a not as described case and get the lot refunded.

Exactly what I was thinking