maybe you can try this :
Reinstall the VPS OS with clean, or just basic OS. No Kloxo, or any control panel.
Check the result of /var/log/secure
Is it only you the one who loging in to VPS? Or there is another person?
Next, move your default ssh port.
And last, change all of your password.

If it still the same, maybe the problem is at the server.