OPay Cashier Reversal Status

$reference    = '12312321324';
$reversalNo = '11212134400034123';
$httpClient = new \GuzzleHttp\Client(); // guzzle 6.3
$response = $httpClient->request('POST', 'https://testapi.opaycheckout.com/api/v1/international/transaction/reversal/status ', [
            'headers' => [
                'Content-Type' => 'application/json',
                'Accept'       => 'application/json',
                'Authorization' : 'Bearer {signature}',
                'MerchantId' : '256612345678901'
            ],
            'body' => json_encode( [
                            'reference' => $reference,
                            'reversalNo' => $orderNo,
                        ] , true)
]);
$response = json_decode($response->getBody()->getContents(), true);
$paymentStatus = $response['type']; // get response values

URL url = new URL ("https://testapi.opaycheckout.com/api/v1/international/transaction/reversal/status ");
HttpURLConnection con = (HttpURLConnection)url.openConnection();
con.setRequestMethod("POST");
con.setRequestProperty("Content-Type", "application/json; utf-8");
con.setRequestProperty("Authorization", "Bearer {signature}");
con.setRequestProperty("MerchantId", "256612345678901");
con.setDoOutput(true);
String jsonInputString = "{
                            'reference'    : '12312321324',
                            'reversalNo'  : '10343543543532432'
                        }";
try(OutputStream os = con.getOutputStream()) {
    byte[] input = jsonInputString.getBytes("utf-8");
    os.write(input, 0, input.length);
}
try(BufferedReader br = new BufferedReader(
  new InputStreamReader(con.getInputStream(), "utf-8"))) {
    StringBuilder response = new StringBuilder();
    String responseLine = null;
    while ((responseLine = br.readLine()) != null) {
        response.append(responseLine.trim());
    }
    System.out.println(response.toString());
}

using System;
using System.IO;
using System.Linq;
using System.Net;
using System.Text;
using Newtonsoft.Json;
namespace OPayRequest
{
    public class Program
    {
        static void Main(string[] args)
        {
            PostJson("https://testapi.opaycheckout.com/api/v1/international/transaction/reversal/status ", new opay_request
            {
                reference    = '12312321324',
                reversalNo  = '10343543543532432',
            });
        }

        private static void PostJson(string uri, opay_request postParameters)
        {
            string postData = JsonConvert.SerializeObject(postParameters);
            byte[] bytes = Encoding.UTF8.GetBytes(postData);
            var httpWebRequest = (HttpWebRequest) WebRequest.Create(uri);
            httpWebRequest.Method = "POST";
            httpWebRequest.ContentLength = bytes.Length;
            httpWebRequest.ContentType = "text/json";
            using (Stream requestStream = httpWebRequest.GetRequestStream())
            {
                requestStream.Write(bytes, 0, bytes.Count());
            }
            var httpWebResponse = (HttpWebResponse) httpWebRequest.GetResponse();
            if (httpWebResponse.StatusCode != HttpStatusCode.OK)
            {
                string message = String.Format("GET failed. Received HTTP {0}", httpWebResponse.StatusCode);
                throw new ApplicationException(message);
            }
        }
    }

    public class opay_request
    {
        public string reference { get; set; }
        public string reversalNo { get; set; }
    }
}