Unable to cancel my PREPAID NOW StreamSaver

I had the PREPAID NOW Internet and StreamSaver. I switched to the POST-PAID Xfinity Internet and NOW StreamSaver and those services were activated yesterday.  I was able to cancel my PREPAID NOW Internet, but I can't cancel the PREPAID NOW StreamSaver.  I get the following error message: "This information is unavailable at the moment, or it didn't load as expected." I tried it multiple times and I get the same error message every time.

I can't activate Netflix, Peacock, and AppleTV+ under my POST-PAID NOW Streamsaver because they are currently active under my PREPAID NOW StreamSaver.

How do I cancel my PREPAID NOW StreamSaver?  I DO NOT want to cancel my POST-PAID NOW StreamSaver.