How to call a Service in symfony2 for multiple times in one controller

I have service called "sms" that I need to use it multiple times in it's controller:

$this->get('sms')->send($userCard->getUser()->getMobile(), "text to send for first time");

$this->get('sms')->send($userCard->getUser()->getMobile(), "my second text to send");

but always it send first message twice, what should I do?

class SmsListener {
    private $url="http://www.smsprovider.com/URLSend.aspx?Username=adminuser&Password=addminpassword&PortalCode=6496&Flash=0&Message=%s&Mobile=%s";
    public function __construct() {
    }

    //put your code here
    public function send($mobile,$message) {

        $this->url=sprintf($this->url,$message,$mobile);

        $url = str_replace(" ", '%20', $this->url);
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch, CURLOPT_URL, $url);
        $ret=curl_exec($ch);
        return $ret;
    }

}

generate your url inside the function like this:

class SmsListener {

        public function __construct() {
        }

        //put your code here
        public function send($mobile,$message) {
            $baseUrl=$url="http://www.smsprovider.com/URLSend.aspx?Username=adminuser&Password=addminpassword&PortalCode=6496&Flash=0&Message=%s&Mobile=%s";
            $url=sprintf($baseUrl,$message,$mobile);

            $url = str_replace(" ", '%20', $url);
            $ch = curl_init();
            curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
            curl_setopt($ch, CURLOPT_URL, $url);
            $ret=curl_exec($ch);
            return $ret;
        }

    }