My C# web service client sends following soap message to Java-based web service:

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope"
               xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
               xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<soap:Body>
<getData>
<request>
<requestParameters xmlns="http://b...">
<equals>
...
</equals>
</requestParameters>
</request>
</getData>
</soap:Body>
</soap:Envelope> 

and Java-based web service returns error:

500 Internal Server Error
...
Cannot find dispatch method for {}getData
...

Client written in Java, which works, sends the following message:

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope"
               xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
               xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<soap:Body>
<ns2:getData xmlns:ns2="http://a...">
<ns2:request>
<ns3:requestParameters xmlns:ns3="http://b...">
<ns3:equals>
...
</ns3:equals>
</ns3:requestParameters>
</ns2:request>
</ns2:getData>
</soap:Body>
</soap:Envelope> 

Is there an easy way in C# to send SOAP messages the same way Java client sends: with namespace prefixes?

Following is C# code that sends message:

// class MyService is auto-generated using wsdl.exe tool
MyService service = new MyService();

RequestMessage request = new RequestMessage();
...

ResponseMessage response = service.getData(request);
...

UPDATE:

RequestMessage class looks like this:

/// <remarks/>
[System.CodeDom.Compiler.GeneratedCodeAttribute("svcutil", "3.0.4506.2152")]
[System.SerializableAttribute()]
[System.Diagnostics.DebuggerStepThroughAttribute()]
[System.ComponentModel.DesignerCategoryAttribute("code")]
[System.Xml.Serialization.XmlTypeAttribute(Namespace="http://uri.etsi.org/02657/v1.5.1#/RetainedData")]
public partial class RequestMessage
{

    private byte[] requestPriorityField;

    private RequestConstraints requestParametersField;

    private string deliveryPointHIBField;

    private string maxHitsField;

    private NationalRequestParameters nationalRequestParametersField;

    private System.Xml.XmlElement anyField;

    /// <remarks/>
    [System.Xml.Serialization.XmlElementAttribute(DataType="hexBinary", Order=0)]
    public byte[] requestPriority
    {
        get
        {
            return this.requestPriorityField;
        }
        set
        {
            this.requestPriorityField = value;
        }
    }

    /// <remarks/>
    [System.Xml.Serialization.XmlElementAttribute(Order=1)]
    public RequestConstraints requestParameters
    {
        get
        {
            return this.requestParametersField;
        }
        set
        {
            this.requestParametersField = value;
        }
    }

    /// <remarks/>
    [System.Xml.Serialization.XmlElementAttribute(Order=2)]
    public string deliveryPointHIB
    {
        get
        {
            return this.deliveryPointHIBField;
        }
        set
        {
            this.deliveryPointHIBField = value;
        }
    }

    /// <remarks/>
    [System.Xml.Serialization.XmlElementAttribute(DataType="integer", Order=3)]
    public string maxHits
    {
        get
        {
            return this.maxHitsField;
        }
        set
        {
            this.maxHitsField = value;
        }
    }

    /// <remarks/>
    [System.Xml.Serialization.XmlElementAttribute(Order=4)]
    public NationalRequestParameters nationalRequestParameters
    {
        get
        {
            return this.nationalRequestParametersField;
        }
        set
        {
            this.nationalRequestParametersField = value;
        }
    }

    /// <remarks/>
    [System.Xml.Serialization.XmlAnyElementAttribute(Order=5)]
    public System.Xml.XmlElement Any
    {
        get
        {
            return this.anyField;
        }
        set
        {
            this.anyField = value;
        }
    }
}