Export Old Invoices in Bulk

var client = new RestClient("https://apitest.nilvera.com/einvoice/Old/Export/Xml");
client.Timeout = -1;
var request = new RestRequest(Method.POST);
request.AddHeader("Authorization", "Bearer <API KEY>");
request.AddHeader("Content-Type", "application/json");
var body = @"["22d6b2ca-ba6b-47dc-a07e-846cc0e51a0e"@"]";
request.AddParameter("application/json", body,  ParameterType.RequestBody);
IRestResponse response = client.Execute(request);
Console.WriteLine(response.Content);