well, it seems your website is defaced, as i read in the first post, not hacked. there is a serious difference between a defacement and hacked server.
Defacement of a server means that they gained access thru a scripting error, a mysql injection or a backdoor in a (nulled) script. But it is not restricted to scripting only, it could mean that your server is running not up to date software (apache, php, exim, or whatever is installed and running)
How to proceed, make sure that on your end you have up to date software, install security patches everytime they are released, keep your server up to date (or ask your hoster) Tell your hoster that you have been defaced (ask maybe for access, error and other logs regarding your domain as you cannot reach it yourself)
Overlook your directories for malicious code, sometime they are able to upload just a bit of code and redo the defacement, and as i see in you first post the guy or girl who did this is posting it to let you know there is a security flw in you config or scripting, google his/her name maybe you might find a solution to your problem. Or even a contact email and ask him what he/she did and how to solve it.
there is mostly one solution to defacements: update update update over and over again.