Thanks @dx100uk @cmas for your reply
Letter is addressed to me with my company address ..i guess they took everything from my website ..
This is my small company which is in struggling phase trying to do something ..don't have any money to give it to them ..i dot not have any registered office in Germany and company is registered in India..
What i should do guys suggest me ??
It seems they have my company details, my details, ip address they monitored