Modern Combat 5 help ?

Wanted to know how can I unlock the Chapter 4 San Marco of MC5 It requires 90 mission service stars and requires you to be a part of the squad How do I get 90 stars and how do I become part of squad as it requires
invitation to become a squad member.
I really don't the answer for what you asked. The reason why I'm here is to appreciate the persona who brought this amazing game in market. It is one of my favorite I have ever played.