var request = require('request');
var options = {
  'method': 'GET',
  'url': '{{BASE_API_URL}}/v2/chargebacks?flwref=FLW-MOCK-8bceeddd2eff1a28d10db65c54e5d858',
  'headers': {
    'Content-Type': 'application/json',
    'seckey':  'FLWSECK_TEST-SANDBOXDEMOKEY-X'
  }
};
request(options, function (error, response) { 
  if (error) throw new Error(error);
  console.log(response.body);
});

<?php

$curl = curl_init();

curl_setopt_array($curl, array(
  CURLOPT_URL => "{{BASE_API_URL}}/v2/chargebacks?flwref=FLW-MOCK-8bceeddd2eff1a28d10db65c54e5d858",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 0,
  CURLOPT_FOLLOWLOCATION => true,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "GET",
  CURLOPT_HTTPHEADER => array(
    "Content-Type: application/json",
    "seckey: FLWSECK_TEST-SANDBOXDEMOKEY-X"
  ),
));

$response = curl_exec($curl);

curl_close($curl);
echo $response;

require "uri"
require "net/http"

url = URI("{{BASE_API_URL}}/v2/chargebacks?flwref=FLW-MOCK-8bceeddd2eff1a28d10db65c54e5d858")

http = Net::HTTP.new(url.host, url.port);
request = Net::HTTP::Get.new(url)
request["Content-Type"] = "application/json"
request["seckey"] = "FLWSECK_TEST-SANDBOXDEMOKEY-X"

response = http.request(request)
puts response.read_body

curl --location --request GET '{{BASE_API_URL}}/v2/chargebacks?flwref=FLW-MOCK-8bceeddd2eff1a28d10db65c54e5d858' \
--header 'seckey: FLWSECK_TEST-SANDBOXDEMOKEY-X' \
--header 'Content-Type: application/json'