data contracts in wcf

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C#

WCF

I create a web method "Opn" in WCF and the envelop looks like the below.

<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/">
  <s:Header>
    <Action s:mustUnderstand="1" xmlns="http://schemas.microsoft.com/ws/2005/05/addressing/none">urn:IEhelplineService/Open</Action>
  </s:Header>
  <s:Body>
    <Open>
      <header xmlns:i="http://www.w3.org/2001/XMLSchema-instance">
        <applicationID i:nil="true" />
        <feedbackMode i:nil="true" />
        <sApplicationID i:nil="true" />
      </header>

Open is the web method and header is a parameter (Basically header is a class with datacontract attribute
specified)
applicationID,feedbackmode, and sApplicationID are properties of header class with datamember attribute specified.
Feedback mode is an object of another class with some more properties, how can i make it a wrapper element? I want the soap xml to look like

<Open>
  <header xmlns:i="http://www.w3.org/2001/XMLSchema-instance">
    <applicationID i:nil="true" />
    <feedbackMode i:nil="true" />
       <mode></mode>
       <type></type>
    <sApplicationID i:nil="true" />
  </header>

How can i do it? I tried using message contract iswrapped. But it was not changing.