I need to back up but it says it is disabled and to contact iTunes support

It actually is showing you that you need to connect to your computer and restore your iPhone. You can try this: How to reset your iPhone, iPad, or iPod touch when you forgot your passcode - Apple Support

If you do not have a current backup but you have previously backed up to your computer and it is a trusted device you can connect your iPhone and see if it will do one last backup. If you have not you will have to use whatever previous backup you have.

If it's referring to your account being disabled in the App Store and iTunes, click here and contact Apple Support at a time they're open; if the link doesn't have an option for your country, use this form. Alternatively, back it up to a computer.

This message doesn't appear during the backup itself, but while upgrading iCloud storage. If the iPhone itself was disabled, it wouldn't be saying to contact iTunes Support, and you won't be able to back it up.

(219448)