Don't use Bad Debt. That isn't the condition for you. This is not a Write off; it is awaiting collection.

Create an Other Charge Type item linked to an Other Asset account named for Collections. Use this on a Credit Memo and apply it to the open invoice(s).

Now AR is removed and this is held as a Different Asset, awaiting collection.

The collection is a Deposit entry, and if the customer balance is not fully collected, you would write off the Balance, at that time.