If you are using WHMCS then you will know that following the latest update you can no longer edit the invoice.
We hope the next update will rectify this but in the meantime below is a work around.
Steps in phpMyAdmin
sql
UPDATE tblinvoices
SET status = ‘Draft’
WHERE id = (123, 278);
Replace 123 with the invoice ID.
Once the invoice is back into draft you can edit the details.
We await the next WHCMS update for this to be reverted back.
Contact me if you get stuck.