There are several ways to correct sales invoices in Xero but perhaps the least effective would be to raised a bunch of credit notes.  This could be very time consuming but might also flag up poor bookkeeping practice or other operational issues.

In the example below we can see that there were 3 credit notes all raised on the same day for the same customer.  The reference is also the same which may imply that we have tried to correct an error and have then duplicated the correction causing a bigger issue.  We would need to take another look at this to see if the bookkeeping was correct.

Is there a problem with this particular customer?  What is the process for crediting a sales invoice?