@"<?xml version=""1.0"" encoding=""utf-8""?><soapenv:Envelope xmlns:soapenv=""http://schemas.xmlsoap.org/soap/envelope/"" xmlns:ws=""http://www.paysecure.ru/ws/""><soapenv:Body>
<ws:PushPaymentResult>
<merchant_id>500001</merchant_id>
<ordernumber>298</ordernumber>
</ws:PushPaymentResult></soapenv:Body></soapenv:Envelope>"

[WebService(Namespace = "http://www.paysecure.ru/ws/")]
    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
    [System.ComponentModel.ToolboxItem(false)]
    public class Payment : System.Web.Services.WebService
    {
        [WebMethod]
        public XmlDocument PushPaymentResult(string merchant_id, string ordernumber)
        {
                return ResultManager.Proccess(merchant_id, ordernumber);
        }
    }

@"<?xml version=""1.0"" encoding=""utf-8""?><soapenv:Envelope xmlns:soapenv=""http://schemas.xmlsoap.org/soap/envelope/"" xmlns:ws=""http://www.paysecure.ru/ws/""><soapenv:Body>
<ws:PushPaymentResult>
<ws:merchant_id>500001</ws:merchant_id>
<ws:ordernumber>298</ws:ordernumber>
</ws:PushPaymentResult></soapenv:Body></soapenv:Envelope>"

[System.SerializableAttribute()]
    [XmlRoot(ElementName = "PushPaymentResult", Namespace = "http://www.paysecure.ru/ws/")]
    public class PushPaymentResult
    {
        [XmlElement(Namespace = "")]
        public string merchant_id { get; set; }
        [XmlElement(Namespace = "")]
        public string ordernumber { get; set; }
     }

[WebMethod()]
        public XmlDocument PushPaymentResult(
            [XmlElementAttribute(Namespace = "")]string merchant_id,
            [XmlElementAttribute(Namespace = "")]string ordernumber)
{
....
}