Just went to cancel my Paramount+ Channel from Amazon Prime, and was offered to keep Paramount+ and pay just A$5.00 per month for 3 months.
May also apply to other subscribed channels, unfortunately I'm only subscribed to P+ so can't check.
Steps:
1. Login to primevideo.com
2. Go to: Your Account -> Account and Settings -> Channels -> Cancel Channel
Let me know if it works for other channels.
Might want to reword that title.