Unable to send SMS with SNS via API/SDK

Hello,

I'm trying to use SNS to send Transactional SMS. Used the SDK AWS provides and everything seems OK however doesn't recieve the SMS and nothing appears in the logs. Checked all the possible issues and everything seems fine. No quota issues (requested and got increase), production enabled, no access issues, test SMS from SNS interface working fine, API response seems good (contains everything which should be in the response according to the documentations), etc.

The next step would be to contact AWS so they can check and resolve the issue. However for that i need to pay, which is a bit weird as im already paying for a service which isn't working ...

Any ideas how should i proceed?

Thanks,