How do I cancel an ICloud upgrade?

From this page http://support.apple.com/kb/TS4009, on an iPad you should be able to do it by :

1. From your home screen, tap Settings > iCloud.
2. Tap your iCloud account at the top of the screen.
3. Select your iCloud Storage plan.
4. Tap Downgrade Options and follow the prompts.

That page also has instructions for doing it via a Mac and PC. Do those instructions not work ? If not then there are also some troubleshooting steps to try on that page :

• Make sure you are signed in to iCloud with the correct Apple ID:
  • iOS devices: Settings > iCloud
  • Mac: System Preferences > iCloud
  • PC: Control Panel > iCloud
• Verify your credit card information is up-to-date.
• Verify your current billing address is correct, including the listed country and region.

Settings>iCloud>Storage & Backup>Buy More Storage>Downgrade Options>Downgrade or Cancel Plan

http://i1224.photobucket.com/albums/ee374/Diavonex/2c00f95135c9eed5c6916948f6882 8b5.jpg

http://i1224.photobucket.com/albums/ee374/Diavonex/831766aa730e4dc613b2e08dacfda 27a.jpg

Note that your current plan is already paid up for one full year.

Have you tried contacting them via the iCloud support page : http://www.apple.com/support/icloud/contact/