Hello @Marcin van de Ven ,we understand you have questions about the Developer support plan and how to engage with Microsoft Support Engineers to receive answers to your technical questions.
Microsoft Q&A is our first party question and answer platform where enthusiasts, MVPs, and other community experts can engage. The developer support plan that you have purchased also ensures a new experience where you receive business hours access to Support Engineers on Microsoft Q&A with prioritized responses, as the first line of support.
Additionally, if you have issues pertaining to Azure billing or subscription management, you can always create a support request though the Azure Portal or by following this link.
We would be more than happy to assist you with any technical questions you have here on Q&A. Any time you post a new thread; you will receive a response within 8 business hours (see here for more details on the SLA and subscription benefits).