If the RSS feed URL for your show has changed since it was originally submitted to Spotify, you'll need to email Spotify's support team to ask them to update it.
You can reach them at firstname.lastname@example.org.
Here's a template you can copy and paste into your email message (just be sure to fill in the required information before you send it).
Subject: Updating RSS feed URL for my show
The RSS feed URL for my show has recently changed. Please update your system to use my new feed URL.
The name of my show is: [NAME OF SHOW HERE]
The old RSS feed URL is: [OLD FEED URL]
The new RSS feed URL is: [NEW FEED URL]
My Spotify account's email address is: [SPOTIFY ACCOUNT EMAIL ADDRESS]
* * *
Looking for your show's current RSS feed? You can find it in your Show Distribution page.
Still have questions? Feel free to email Spotify's support team using the email address provided above, or you can reach Simplecast support using the chat icon down there on the right side of your screen.