Are you having problems actually buying the Silver from your platform store, or did you successfully buy it and it is not showing up in game?
If the former, then you need to contact your platform support to resolve issues with purchasing items from their store.
If the latter, you can reading through the silver FAQ page TheHaraamPolice linked to in their post.
Hey there! Please follow this link and fill out Bungie’s [url=https://www.bungie.net/en/Support/Troubleshoot?oid=13657]Missing Silver Contact Form[/url] at the bottom of the page once you have done all of the troubleshooting steps listed in the article.
All contact forms are currently down at the moment which is something Bungie is investigating. You can fill out the contact form when it is up and running.