Hello glucc,
Thanks for using the Apple Support Communities!
From your post, I understand that you are dissatisfied with an application your purchased form the App Store. It doesn’t sound like you are looking for support, but I would like to try and assist if possible.
If the application isn’t performing the tasks or performing as you would expect, my first recommendation would be to contact the developer for assistance. Instructions on how to contact a developer can be found in the following article, but for your convenience I have included their direct support link as well.
If an app you installed unexpectedly quits, stops responding, or won’t open - Apple Support
Fax to email and iPhone for free with Fax Burner
After looking on their website, if you scroll down to the very bottom of the page and click on their Terms & Conditions, their contact information is located at the very bottom of that page.
If the issue remains unresolved, you can report this problem directly to Apple by using the information in the next article.
Report a problem with an item purchased from the iTunes Store, App Store, Mac App Store, or iBooks Store - Apple Support
Cheers!