Passing invalid xml as string as Post in WCF

I am trying to create a post method in WCF application which takes the XML when the request is made. I was able to make the post method work whenever the client machine send the valid xml in request, however if the xml was invalid (e.g. if it had '&' sign) the post method would never get the request. The reason i want to capture the client's request whether if it has valid or invalid xml request is so that i can log client's request (i.e.xml input). I even created a post method with the string as parameter but still i was not able to debug the application when the request was made.

Here is the setup of post methods in WCF applicaton:

[OperationContract]
[WebInvoke(Method = "POST", 
    ResponseFormat= WebMessageFormat.Json,
    BodyStyle = WebMessageBodyStyle.Bare,
    UriTemplate = "/PostName/")]
string PostName(string name);

[OperationContract]
[WebInvoke(Method = "POST",
    ResponseFormat = WebMessageFormat.Json,
    BodyStyle = WebMessageBodyStyle.Bare,
    UriTemplate = "/PostNameXml/")]
string PostNameXml(XElement name);

Here is the invalid xml input:

<?xml version="1.0"?>
<catalog>
   <book id="bk101">
      <author>Gambardella, Matthew</author>
      <title>XML Developer's Guide</title>
      <genre>Com&puter</genre>
      <price>44.95</price>
      <publish_date>2000-10-01</publish_date>
      <description>An in-depth look at creating applications with XML.</description>
   </book>
</catalog>

Here is what my web.config looks like:

 <services>
   <service behaviorConfiguration="ServiceBehavior" name="WCFTest.Service1">
     <endpoint address="" behaviorConfiguration="webBehavior" binding="webHttpBinding" contract="WCFTest.IService1" />
   </service>
 </services>

 <behaviors>
   <endpointBehaviors>
     <behavior name="webBehavior">
       <webHttp />
     </behavior>
   </endpointBehaviors>

   <serviceBehaviors>
     <behavior>
       <serviceMetadata httpGetEnabled="true"/>
       <serviceDebug includeExceptionDetailInFaults="false"/>
     </behavior>
     <behavior name="ServiceBehavior">
       <serviceMetadata httpGetEnabled="true"/>
       <serviceDebug includeExceptionDetailInFaults="false"/>
     </behavior>
   </serviceBehaviors>
 </behaviors>

 <serviceHostingEnvironment multipleSiteBindingsEnabled="true" />

Do let me know if this can be done or not? Thanks.

Sanjeev