// Define array of request body.
$request_params = [
    'merchant' => '123456',
    'test' => '1',
    'price' => '1000',
    'curr' => 'CZK',
    'label' => 'Product 123',
    'refId' => 'order445566',
    'method' => 'ALL',
    'email' => 'platce@email.com',
    'prepareOnly' => '1',
    'secret' => 'gx4q8OV3TJt6noJnfhjqJKyX3Z6Ych0y',
    'fullName' => 'Jan Novák', // nové parametry ↓
    'billingAddrCity' => 'Hradec Králové',
    'billingAddrStreet' => 'Jiráskova 115',
    'billingAddrPostalCode' => '50341',
    'billingAddrCountry' => 'CZ',
    'delivery' => 'HOME_DELIVERY',
    'homeDeliveryCity' => 'Pardubice',
    'homeDeliveryStreet' => 'třída Míru 224',
    'homeDeliveryPostalCode' => '54314',
    'homeDeliveryCountry' => 'CZ',
    'category' => 'PHYSICAL_GOODS_ONLY',
];

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, 'https://payments.comgate.cz/v1.0/create');
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($request_params));
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);