Hi,
Unfortunately, Microsoft discontinued direct phone support for home users several years ago, and support requests now typically start through online chat.
If the issue you are experiencing is a Microsoft Store bug or glitch, the best place to report it is through the Feedback Hub app in Windows. Feedback submitted through Feedback Hub goes directly to Microsoft's engineering teams and allows you to provide details, and screenshots that can help them investigate the problem.
To submit feedback, press Windows + F on your keyboard to open the Feedback Hub app, then provide detailed information about the issue you are experiencing and submit your report.
The more details you include, the easier it will be for Microsoft to investigate the problem.
Could you provide more details about the Microsoft Store download problem? For example, do downloads fail, get stuck at a certain percentage, show an error code, or not start at all? I may be able to help troubleshoot the issue.