I signed up to the 50GB storage plan and have 46GB storage left however I'm still getting the same 'Storage Full - Manage your storage in settings' message. I have turned off certain apps etc.

Hello __asmith,

Thanks for using Apple Support Communities.

I understand you're getting a message that your storage is full. Given you have plenty of iCloud storage available, the message might be telling you about the storage on your iOS device itself. To learn how you can manage the storage of your iOS device, please take a look at the link below.

Check your storage on your iPhone, iPad, and iPod touch

Take care.