Your customer has two quotes, paid for one but then changed their minds and wants the other (unpaid) quote. This article will show you how to remove the payment from the incorrect quote.
1. Remove the payment in Xero and apply it to the correct invoice. Continue as per normal.
To fix & void the old invoice:
2. Go into Lightspeed > Sell > Sales history > Sales ledger.
Click on 'more filters'
Find the customer or the invoice
Click update
Click on the dropdown and find the Xero payment.
Remove it.
3. Once this is done, let us know so that we can ask the vendor to change the status from 'paid' to 'unpaid'.
4. Once that is done, you can safely void all three invoices in all three systems.