Hello there, @vitanovabookkeeping. Looks like you've posted twice in this forum.
If you have tried creating a refund receipt and matching it with the downloaded transaction from your bank feeds and it's not working, please give us a short call. We'll need to look at your account in detail, and this can only be done by contacting our specialist. This way, we'll be able to ensure we're reviewing your account in a secure environment.
My colleague already shared the steps on how you can connect to our support team. Please see the complete details in this article: Change the amount.
You can go back to this thread if you have other questions in mind. Take care and stay safe.