[GNC] Correcting an over payment on an invoice

[Michael Campbell]

I was just reconciling the last quarters books and could not get the damn things to reconcile. I finally tracked it down to a client overpaying on an invoice by a small amount, transposing some digits on the invoice.
Now I am no accountant.
I thought I could fix the books by just sending the client  another invoice of the difference, with a nice funny charge.
Is there any way I can change the date of an invoice in GNUCash to last month to reconcile to the bank statements?
Is there a more correct accounting way to correct this?
Thanks,

Michael Campbell