php curl login not work, code tested with other site

Question

I have a problem with curl remote login, i don't know what the issue , tried the code with other site working but with my customer website not working

function get_cURL() {

        $url = "https://qualitycarrentalltd.com/admin/login.php";
        $ch = curl_init($url);
        $credentials = "user=myusername&pass=mypassword&Submit=Login";
        curl_setopt($ch, CURLOPT_HEADER, false);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $credentials);
        curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);

        curl_setopt($ch, CURLOPT_POST, true);
    curl_setopt($ch, CURLOPT_HTTPHEADER, array('Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8','Accept-Language:     en-us,en;q=0.5','Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7','Keep-Alive: 115','Connection: keep-alive'));

        curl_setopt($ch, CURLOPT_COOKIEJAR, 'cookie-name.txt');
        curl_setopt($ch, CURLOPT_COOKIEFILE, 'cookie-name.txt');

        $result = curl_exec($ch);
        curl_close($ch);

        return $result;
}

var_dump(get_cURL());

another code

$url = 'https://qualitycarrentalltd.com/admin/login.php';
$data = array('user' => 'myusername', 'pass' => 'mypassword', 'Submit' => 'Login');

// use key 'http' even if you send the request to https://...
$options = array('http' => array(
    'method'  => 'POST',
    'content' => http_build_query($data)
)
);

$context  = stream_context_create($options);
$result = file_get_contents($url, false, $context);

print_r($result);

Why login not working? it take days from me without found solution, Can someone help with fix Please