PHP To XML API

Hello People,
i have php data that i should send to my API provider who requested the data to be in XML format like this:

I am getting data from a form that has a PAY NOW button.

if(isset($_POST['pay_now'])){
$userid = $_POST['user-id'];

$total_amount = $_POST['total_amount'];

$currency = $_POST['currency'];

$firstname = $_POST['firstname'];

$lastname = $_POST['lastname'];

$email = $_POST['email'];

$phone = $_POST['phone'];

$reasons = $_POST['reasons'];

$application_id = $_POST['application_id'];

$order_id = password_hash($application_id, PASSWORD_DEFAULT);

$token = "XXXXX";

$payUrl = "https://secure1.sandbox.directpay.online/payv2.php?ID=".$token;
$CompanyRef = "XXXXX";

$CompanyRefUnique = "olord11of2273host";

$RedirectURL = "www.mydomain.com/example?success=".$CompanyRefUnique."&congrats=".$CompanyRef."&user=".$userid;

$DeclinedURL = "www.mydomain.com/example?paymentdecline=".$CompanyRef."&user=".$userid;

$PTLtype = 20 ." minutes";

$DefaultPayment = "MO";

$ServiceDescription = $reasons;

$ServiceType = "5525";

$ServiceDate = date("YⓂ️d: hⓂ️ ")

$datainput = '


'.$total_amount.'

                <PaymentCurrency>'.$currency.'</PaymentCurrency>

'.$RedirectURL.'

'.$DeclinedURL.'

                      <CompanyRefUnique>'.$CompanyRefUnique.'</CompanyRefUnique>

                        <CompanyRef>'.$CompanyRef.'</CompanyRef>

'.$PTLtype.'

                        <customerFirstName>'.$firstname.'</customerFirstName>

                        <customerLastName>'.$lastname.'</customerLastName>

'.$email.'

                        <DefaultPayment>'.$DefaultPayment.'</DefaultPayment>

'.$ServiceType.'
'.$ServiceDescription.'
'.$ServiceDate.'

</Services>

';

    $ch = curl_init($payUrl);

            curl_setopt($ch, CURLOPT_URL, $payUrl);

            curl_setopt($ch, CURLOPT_HTTPAUTH, CURLAUTH_ANY);

            curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);

            curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 0);

            curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);

            curl_setopt($ch, CURLOPT_SSLVERSION,6);

            curl_setopt($ch, CURLOPT_HTTPHEADER, array('Content-Type: text/xml'));

            curl_setopt($ch, CURLOPT_POSTFIELDS, $datainput);

            $response = curl_exec($ch);

            curl_close($ch);

}

I am not getting any errors, but am not getting a redirect to the sandbox url. How can i make the Paynow Button to work like that?