cPanel overwrites css folder contents

Hi
I bought a shared hosting space and installed Wordpress and a Woocommerce theme on it.
There is a css folder that contains stylesheet files of the theme.
I edit proper css file, save it, refresh the site and no change. Then i open the css and changes are back.
Even if i delete the css file and hit reload, file re-apear after a moment!!
Using ftp clients like FileZilla to download, edit and upload file didn't help either.
I've never faced this before and really need to edit appearance of the site editing stylesheets.
I appreciate any help.

 

Unfortunately there's no good support in Wordpress forums!
But i'll try.
Thanks