Right now it looks like partial filehosting (backup perhaps) as you have a complete copy of your homedir located in a folder named "_" (just un underscore). This folder seem irrelevant to your site and makes up for about double the space taken.
If the intention is to have a backup, I'd advise you to download that folder and then deleting the folder on the server, if it is purely a mistake you can safely delete that folder. For backup purposes you really only need files in public_html, as well as a copy of the database, though as most other files and folders in homedir does have some ownership/permissons that may prevent them from working properly when restored from such a backup.
Could you please clarify the reasons for that folder, and make sure you take care of it properly. Without it you would fall under the limit for space increase so at this point the increase is denied.