So it's confirmed to be a prequel, then. Wow.

By the way, for those curios, the dialogue from the phone guy on night 6:

"Hello? Hello…uh…what on earth are you doing there, uh didn’t you get the memo, uh, the place is closed down, uh, at least for a while. Someone used one of the suits. We had a spare in the back, a yellow one, the one used in…now none of them are acting right. Listen j-just finish your shift it’s safer than trying to leave in the middle of the night. Uh we have one more event scheduled for tomorrow, a birthday. You’ll be on day shift wear your uniform, stay close to the animatronics, make sure they don’t hurt anyone okay, uh for now just make it through the night, uh when the place eventually opens again I’ll probably take the night shift myself. Okay, good night and good luck."

I know how you feel, but here is what I think.

It all started with one place with the original four. It was somewhat successful but general incompetence gave it a negative impression. So they moved to a new location, bought new animatronics (and salvaged parts from the old ones to make money) and reopened. However, either your player character has a criminal record (something minor like petty theft) that causes the robots to attack or, as one of the phone calls says, the new ones are just glitchy, while the old ones still only go nuts at night, just like in the first game. That puppet, of all things, causes the bite of 87 and kills the four kids that gets bounded to the old suits, so they have no choice but to close down the new location. Since only the new ones acted weird during the day, they get scrapped but the old ones are repaired and taken back to the old location, since no one knows they're actually haunted. So there you go. The only question remaining is what happened at the old location before either of the first two games.