Pass XML as input parameter in WS

A have a web method with input parameter type of string. But this parameter actually is not string but xml. The example of input is:

<![CDATA[<check>
  <id>12354564</id>
  <idMeaning>msisdn</idMeaning>
<amount>500</amount>
</check>]]>

Bellow is snipped form my code where i create the input and call the method

// create xml
var xml = new XElement("check",             
                new XElement("id", "41504823"), 
                new XElement("idMeaning", "msisdn"),
                new XElement("amount", "500")
                );      

// add CDATA
var input = new XCData(xml.ToString());

// get client
var client = WSWrapper.GetClient();

// call method
client.DoCheck(input.ToString());

But then I have problems with encoding. If I check request over the wire I can see that xml has been encoded like

 <![CDATA[<check>
 <id>41504823</id>
 <idMeaning>msisdn</idMeaning>
 <amount>500</amount>
 </check>]]&gt

How can I prevent this encoding?