Another website is pointing A record to my website

My first post here. I had a huge problem and ill try to explain the best i can and i 'm sorry if i posted in wrong forum… Plastic explanation: I have a website on dedicated server. Someone pointed A record to my website but somehow, though it's shared IP address they displayed my website with they domain name…

Or Like this. I have a website on shared IP on dedicated server called xxx.com and someone pointed A record and they had my website under they domain name like yyy.com and you…

Another website is pointing A record to my website