已超过'max_connections_per_hour'

my hosting pop this kind of error message during a flood of active user using my system online.. "has exceeded the 'max_connections_per_hour'"

Then the server provider said it was my connection code was not optimized.

===========

@session_start();

(CONNECTION VARIABLE ON TOP)

$localhost = mysql_pconnect($hostname_localhost, $username_localhost, $password_localhost) or trigger_error(mysql_error(),E_USER_ERROR); 

@mysql_select_db($database_userdb, $localhost);

@error_reporting(0);

===============

This was the code originally, then the server provider suggested me to change mysql_pconnect into PDO or mysqli connection

Then we change to this

try {

$pdo = new PDO('mysql:host='.$hostname_localhost.';dbname='.$database_userdb, $username_localhost, $password_localhost);

} catch (PDOException $e) {
    echo $e->getMessage();
}

And that error "has exceeded the 'max_connections_per_hour'" still pop up.. And today the server provider suggested me that "the script should be using a persistent MySQL connections.", so am I going to change back the PDO into mysql_pconnect which is persistent MYSQL connection that we use originally..

Both connection works fine on the system, just that with a massive flow of traffic into the system, that error pops up on my web page..

By the way.. im using include("connection.php"); something like this on the page.. does that effect my persistent connection?

And how do I resolve this matter? Please help me..