Web services eliminating weak ciphers

We have an application that calls out to a Government web services to pulls data into our system. They have eliminating “weak ciphers” and now only support three. I am getting some errors that the system can't create a secure channel. Is there something else I need to do for this to work?

Error

An exception has been thrown: (System.AggregateException: One or more errors occurred. ---> System.Net.Http.HttpRequestException: An error occurred while sending the request. ---> System.Net.WebException: The request was aborted: Could not create SSL/TLS secure channel.

Code

ServicePointManager.SecurityProtocol =
                SecurityProtocolType.Ssl3 |
                SecurityProtocolType.Tls |
                SecurityProtocolType.Tls12;

Service Code

private T Run<T>(string url, string queryString) where T : new()
        {
            T result = default(T);

            using (var client = new HttpClient())
            {
                client.BaseAddress = new Uri(url);
                client.DefaultRequestHeaders.Accept.Clear();
                client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

                using (HttpResponseMessage response = client.GetAsync(queryString).Result)
                {
                    if (response.IsSuccessStatusCode)
                    {
                        result = response.Content.ReadAsAsync<T>().Result;
                    }
                    else
                    {
                        throw new Exception($"Resourse {url}{queryString} failed: {(int)response.StatusCode} ({response.ReasonPhrase})");
                    }
                }
            }

            return result;
        }

Currently supported ciphers:

TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 
TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 
TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256