If it lists itself as a specific user-agent, then you should be able to put together a .htaccess to block or redirect any access attempts it makes. For several tips on how to do this, you can google for ".htaccess block by user-agent" without the quotes and several decent results come up.
Well, when you checked your logs, what did they have listed as the user-agent? I do assume also that you took the user-agent you found in the logs and entered it in the place of the examples such as ^BadBot etc. If you know their IP addresses, then you probably can block their network blocks via iptables.
You mentioned "Tried these but same. .", and I am not sure you have mentioned what "the same" is. If you could describe what is happening that is alerting you to knowing that "the same" is happening, I may be able to leverage that information into more of an intelligent solution.
What does it look like in the logs when they are scanning your site? From what I can tell, when they scan, they tend to scan more than just apache, and in that case, blocking them via iptables would be the best bet.