I pulled one of my public functions, as you can see I did skip the tick marks for the variables, albeit I can't for the life of me remember why. Maybe give it a shot without the variable ticks.
public function addUserNotes($suids, $CID, $note){
$query = $this->mysqli->prepare("INSERT INTO `Notes` (`Contact_ID`, `UID`, `Note`) VALUES (?, ?, ?)");
$query->bind_param("sis", $CID, $suids, $note);
$query->execute();
$query->close();
Note:
I notice you declared php twice, I'm not a php expert so excuse me if it's an obvious answer. Can you declare php twice in the same script? What would be the benefits to doing that?