iPhone, iPad, or iPod touch:

1. If you're using iOS 8 or later, go to Settings > iCloud > Storage. If you're using an earlier version of iOS, go to Settings > iCloud > Storage & Backup
2. Tap Buy More Storage or Change Storage Plan.
3. Choose an upgrade, then tap Buy and enter your Apple ID password.

iCloud storage upgrades and downgrades - Apple Support

I received an unsolicited notice of an unrequested update that had been made on my icloud storage, with a monthly charge. it states that I have 15 days to downgrade back to my original plan, cancel the upgrade. where can i send my cancel and refund request?

How do I cancel my monthly iCloud storage plan?

What if I have no apple products? Can I do it on icloud.com? Ive been trying to. I'm hoping to avoid calling in.

You can do it on a PC via iCloud For Windows, the instructions are in the link on the first reply

I DON'T WANT TO BUY I WANT TO CANCEL AND WANT YOU TO STOP CHARGING MY CARD...YOU'RE RIPPING ME OFF YOUR WEBSITE DOES NOT CANCEL THEY SELL, SELL, SELL - NEED HELP!

We are not charging you, we are fellow users that you are shouting at, these are user-to-user forums. Use the instructions already posted to downgrade

I am searching also on how to cancel my monthly storage plan. There is no where to cancel once you upgrade?

Yes there is, follow the instructions in the link on the first reply