First read the Getting Started (https://docs.barion.com/Getting_started) and the Troubleshooting (https://docs.barion.com/Troubleshooting) sections of the documentation.

If that did not help, you can join the Barion Developers community at https://www.facebook.com/groups/bariondevelopers and ask the community members.

If you are still stuck, write a mail to devsupport@barion.com with:

• A thorough description of your issue.
• Any ID-s you have, such as account e-mail, shop name, transaction ID, etc.
• Don't forget to state which server are you using: Live or Sandbox.
• The JSON that you submitted and did not work.
• A screenshot, if relevant.
• Your phone number or Skype, so we can call you with questions.