Cielo’s integration with C# and Asp.Net MVC?

Question

I’m trying to integrate Cielo to make payments on my site "Asp.Net MVC" but I’m not getting it. I read the Cielo integration manual, followed all the steps, performed tests in Postman and works well, but in my application I am not able to make it work, always returns the error: Method Not Allowed and looking at Cielo’s website, I couldn’t find a way to solve this problem.

For integration, I tested using Httpclient and Restsharp and both return the same error.

How to solve this problem ?

//pagamento com cartão
public static bool Pay(CieloObject obj){

        try{
            string URL_FINAL = "https://apisandbox.cieloecommerce.cielo.com.br";
            string mid = "<meu-id>";
            string key = "<minha-chave>";

            var request = new RestRequest();
            request.Method = Method.POST;
            request.AddHeader("content-type", "application/json");
            request.AddHeader("Accept", "application/json");
            request.AddHeader("MerchantId", mid);
            request.AddHeader("MerchantKey", key);
            request.Parameters.Clear();
            request.AddParameter("application/json", JsonConvert.SerializeObject(obj), ParameterType.RequestBody);             

            System.Net.ServicePointManager.SecurityProtocol = System.Net.SecurityProtocolType.Tls12;
            var client = new RestClient(URL_FINAL);
            var response = client.Execute(request);

            Debug.WriteLine(response.StatusDescription);


            return true;
        }catch(Exception e){

            return false;
        }       

       
    }