MYSQLi error: User already has more than 'max_user_connections' active connections

I have this error below on a site I am running. I don't understand why is that as it works fine on my localhost. Is it something to do with the host? I am on an Unix server.

Warning: mysqli::mysqli() [mysqli.mysqli]: (42000/1203): User dbo343879423 already has more than 'max_user_connections' active connections in /homepages/9/d322397966/htdocs/dump/models/class_database.php on line 11
Connect failed: User dbo343879423 already has more than 'max_user_connections' active connections 
Warning: mysqli::close() [mysqli.close]: Couldn't fetch mysqli in /homepages/9/d322397966/htdocs/dump/models/class_database.php on line 160

the error says 'User dbo343879423 already has more than 'max_user_connections' active connections in /homepages/9/d322397966/htdocs/dump/models/class_database.php on line 11', so this is the line 11 in the script - I can't see anything wrong!

$this -> connection = new mysqli($hostname,$username,$password,$database);

below is the entire class in class_database.php, is it wrong in other part of script and I should change?

<?php
#connects the database and handling the result
class __database {

    protected $connection = null;
    protected $error = null;

    #make a connection
    public function __construct($hostname,$username,$password,$database)
    {
        $this -> connection = new mysqli($hostname,$username,$password,$database);

        if (mysqli_connect_errno()) 
        {
            printf("Connect failed: %s\n", mysqli_connect_error());
            exit();
        }
    }

    #fetches all result rows as an associative array, a numeric array, or both
    public function fetch_all($query) 
    {
        $result = $this -> connection -> query($query);
        if($result) 
        {
            return $result -> fetch_all(MYSQLI_ASSOC);
        } 
        else
        {
            $this -> error = $this -> connection -> error;