CRM web service timeouts on workflow activites

I'm on CRM online 2015 and using workflow activities to call my custom web services. This takes about 10 minutes to return a response for some of the service methods. I'm adding enough time, but CRM online keeps timing out. Code is below: 

BasicHttpBinding myBinding = new BasicHttpBinding();
myBinding.Name = "BasicHttpBinding_MyService";
myBinding.OpenTimeout = new TimeSpan(0, 20, 0);
myBinding.CloseTimeout = new TimeSpan(0, 20, 0);
myBinding.SendTimeout = new TimeSpan(0, 20, 0);
myBinding.ReceiveTimeout = new TimeSpan(0, 20, 0);
myBinding.Security.Mode = BasicHttpSecurityMode.None;
myBinding.Security.Transport.ClientCredentialType = HttpClientCredentialType.None;
myBinding.Security.Transport.ProxyCredentialType = HttpProxyCredentialType.None;
myBinding.Security.Message.ClientCredentialType = BasicHttpMessageCredentialType.UserName;
EndpointAddress endPointAddress = new EndpointAddress(strServiceURL);
using (MyServiceClient client = new MyServiceClient(myBinding, endPointAddress))
{
response = client.CreateContact("Testing");
}

Any other way to increase the length of time to wait for a response?