Error sending XML / string to web services C #

I have the SoapUI where I am doing a web services test in which I add 3 data to the request and it gives me an answer, until here everything is fine.

It happens that I want to consume that webservice using C #, the code I have so far is:

private void button1_Click(object sender, EventArgs e)
        {

            string uno = "2018-12-05T17:00:00";
            string dos = "3101009059";
            string tres = "2018-11-28T00:00:00";

            string xmlData = @"<con:contractNoticeReqBean>
                                 <java:End_ymd>"+uno+ @"</java:End_ymd>
                                 <java:Inst_reg_no>"+dos+@"</java:Inst_reg_no>
                                 <java:Start_ymd>"+ tres + @"</java:Start_ymd>
                              </con:contractNoticeReqBean>";

            XmlDocument xmlDoc = new XmlDocument();
            xmlDoc.LoadXml(xmlData);

            ServiceReference1.ContractInfoWServiceClient client = new ServiceReference1.ContractInfoWServiceClient();
            var data = client.getRequestContractNotice(xmlDoc);


        }

But when I run the code it throws me an error in the line xmlDoc.LoadXml(xmlData); the error is:

  

System.Xml.XmlException: '' with 'is an undeclared prefix. line 1,   position 2. '

If I try to send the string xmlData the error that points me before I can run the code in line var data = client.getRequestContractNotice(xmlDoc); is:

  

Argument 1: Unable to convert from 'System.Xml.XmlDocument' to   'xml.ServiceReference1.ContractNoticeReqBean'

How can I solve this in order to be able to send those 3 data correctly?

EDITED

Edit it in this way to send the data:

private void button1_Click(object sender, EventArgs e)
        {

            DateTime final = DateTime.Parse("2018-12-05T17:00:00");
            string ints = "3101009059";
            DateTime inicio = DateTime.Parse("2018-11-28T00:00:00");

            ServiceReference1.ContractNoticeReqBean reqBean=new ServiceReference1.ContractNoticeReqBean();
            reqBean.End_ymd = final;
            reqBean.Inst_reg_no = ints;
            reqBean.Start_ymd = inicio;

            ServiceReference1.ContractInfoWServiceClient client = new ServiceReference1.ContractInfoWServiceClient();
            var data = client.getRequestContractNotice(reqBean);
            listBox1.Items.Add(data);


        }

I want to receive this information:

But my way out is this:

What is my fault now?