Returned Orders

Hello guys,

I am wondering how do you deal with returned items?

I have Cash on Delivery payment and some clients doesn't accept the shipment and the company returns it back to me. Some of them pay and then want to cancel it. in this case, I don't want to just cancel the order because it will be accounted already. Is there anyway where I can reverse the transaction instead of cancelling it? For example negative quantity or any other solution?

Please share your experience.