My Box is empty but it says it's almost full.

Hi, after I've deleted some files I've noticed that the size of free space was incorrect.
I've waited one day to see if it was updating but it doesn't. 
So I've deleted all my stuff (also the trash is empty), but after two other days it's not updating the correct free space so I can't use the service anymore.
I've seen many people have the same problem, but looks like there's nothing that an user can do... besides ask for a fix from the staff.
Can someone fix the used size of my box please?