Help - account says I don't have enough storage, even tho I've upgraded account?!

I'm trying to upload a video to my box account, but I keep getting a message saying my storage is full even though I've used less than 1gb. It's an urgent file I need to deliver, and I've even upgraded and paid £11 for a month as I thought this may help but it hasn't. Please can someone help asap? Is there a number for support/or live chat - I can't see any support from BOX on how to access support and speak to someone.