Ensure you're using the most recent version of Bonza by downloading any updates from the App Store.
You might have restrictions on your device preventing you from making in-app-purchases. Go to your device settings, tap “General” and then navigate to “Restrictions” if restrictions are "ON" this may be preventing you from making In-app Purchases.
If you’re still having issues, send an email to email@example.com and include which purchase/s you are having issues with and which version of iOS you have. We will get back to you as soon as we can.