Upgraded to Nitro pdf pro 12 from pdf pen 10, but it is not supported, I want my money back

[Annette Vaandrager]

I purchased an upgrade to pdfpen, which is v.12, my money was accepted even though this version is no longer supported, it turns out.  I tried putting the serial number in to upgrade to v.13 or 14, and am getting an error message.
"We were unable to validate your serial number. Please ensure you entered it correctly. If you believe you are eligible for an upgrade, please leave a post on our Community Forum and update us with your issue."

I paid $35 plus tax for something that is not working.  I would like a refund.

 

[Reymund Oyong]

Greetings @Annette Vaandrager

Thank you for reaching out through our Community Forums!

This seems to be under Nitro PDF Pro for Mac. 
The Upgrade Portal, found here https://www.gonitro.com/support/upgrade, is for the Windows licenses.
From what I understand, you use the In-App upgrade in the PDFpen application, and that processed PDFpenPro 12 license. If this is correct, you can submit a refund support case here https://www.gonitro.com/support/ticket/pdf-pro-mac

Kind regards,