If you are having issues with a specific project you’ve bought, the first best thing you can do is check with the creator of the project. They might not be aware of the problem, and letting them know might help fix the issues for other users having similar issues. Or you might have missed something in the install instructions, which you can now resolve.
You can do that by leaving a comment on the project’s page, or directly contacting the developer, if they’ve provided contact details.
If you are certain that you need a refund, support is the only action to help. I’d wait for a response from them.
If possible in the future, it’s better to make a new thread than replying on old ones, as it will increase your chances of someone looking at it.
Hope that helps :)