What do we need to do if l purchase a plugin and the author doesn't reply to support question

We having a problem with the plugin author Prices By User Role for Woo Commerce and we have paid for the plugin and there is no response to our support ticket.

What should we do.

How long ago did you ask for help?

Did you use their support forum? Support : Festi-Team

Depending on what the issue is and how long ago you bought the item then if the author goes entirely silent then you would probably be entitled to a refund