}
if (isset($_POST["taxAmount"])) {
    $taxAmount = $_POST["taxAmount"];
}
if (isset($_POST["serviceId"])) {
    $serviceId = $_POST["serviceId"];
}
if (isset($_POST["productId"])) {
    $productId = $_POST["productId"];
}
$endpoints = new ServiceEndpoints();
$paymentResponse = null;
if (!isset($submit)) {
    $username = "******";
    $password = "******";
    $endpoint = $endpoints->getAmountReserveEndpoint();
    $endUserId = "tel:+123456789";
    $referenceCode = "REF-12345";
    $description = "Alien Invaders Game";
    $currency = "USD";
    $amount = 10.0;
    $code = "C528";
    $clientCorrelator = "54321";
    $onBehalfOf = "Example Games Inc.";
    $purchaseCategoryCode = "Game";
    $channel = "Wap";
    $taxAmount = 0.15;
    $serviceId = "SID1234";
    $productId = "PID00008765";
} else {
    $endpoints->setAmountReserveEndpoint($endpoint);