Facebook Major Glitch / Hack?

[Mateo]

Someone found the ability to message all of their friends at once. 876 people received the same message and we're all linked into a message conversation. Apparently, his mom got on his Facebook and tried to advertise her store. Nonetheless, we're all stuck with this message that won't go away. People keep replying and we all get notifications, especially to our phones. How in the world can I detag myself from a message series? This is really bad; I've received over 300 texts about a person posting on this giant message

[Rex Hd]

just remove your facebook and make a new one..

[Hard24get]

If you can, get on the computer the person posted on. then clear the cookies and cache. normaly that would fix the most common hacks on facebook. some get more powerfull and with those you need to delete the account altogether