We cannot give refunds ourselves, but you can ask Apple for one.
When you purchase an app from the App Store, only Apple has access to the purchase information that is associated with your Apple Account. If you are not happy with Things, you need to request a refund from Apple. Whether or not a refund will be given is entirely Apple’s decision.
Since Apple doesn’t share information about you with us, we cannot issue refunds.
Here’s how to request a refund: https://support.apple.com/en-us/118223.
If Apple refuses a refund, there is nothing we can do about that. Please discuss your options with a representative from Apple.