Found my folders again but they are empty!

Dear ll,

Yesterday I decided to upgrade my iCloud storage because it had been full for a while. I liked on a few buttons and all of a sudden I lost all my documents including the ones on my desktop. I tried to fix the problem and my folder reappeared on my desktop but they are empty!

My iCloud storage is still full. I am not able to upgrade it. I want to buy the 2.99EUR package but then get blocked with a message "contacting card issuer". I contacted my bank and everything is fine. I confirmed my authentication etc.

How can I proceed with buying this bigger package?

How can I get my documents back?

thank you very much

Stephanie