@Prodigy
Even if I renamed ACP folder in previous host, he managed to know the new name of it and he beaten htaccess too, but after I added Deny All IP except the admins IPs, this step stopped him from entering it.
So we dealing here with someone has experience and he was well aware of site flaws and security holes, it has noting to with "h4x0r3d".
When moved, my forum become more safer.
So it has nothing to do with securty setting by us too.
The lesson I learnt from that, is not go to someone sell hosting with very cheap prices and a lot of advantages for low fees.