If you have your OneDrive free account downgraded to a 5GB plan, you're not alone. But now, there are available a number of ways to add free space to your OneDrive. One way is that if you have a Samsung smartphone or tablet, there's a chance that you are actually entitled to the 100GB free space bonus.
Here's how ...
On your mobile device, make sure your OneDrive is up-to-date, if not, go to Play Store to update it. Then, run OneDrive app and go to Settings. Look for the option "Apply 100GB Samsung offer". If the option is there, congratulations! You are entitled to 2 years' 100GB free OneDrive space! Tab on it and simply follow the on-screen instructions.
After successfully applied, the bonus offer should be reflected on your OneDrive account.
There are a number of other vendors out there offering similar bonus space. Try google them... ;>