How to forward request from one WCF to another WCF?

Question

I have a situation where I have to create a service A (kind of a Proxy service) which will in turn calls another service B (the real service). The client C will only know the service A. Service A will log the call and would just kind of forward the request to B. After it gets a reply from B, A logs the response and sends it back to the client C. To achieve this scenario I have seen many examples but nothing seems to work. I do have a few limitations. I can't add the reference of the service B inside service A. I also can't create service references. Services A and B are totally different and they don't know each other.

    ---->      ---->
C           A           B        
    <----      <----      

In A, inside BeforeSendRequest() of IClientMessageInspector, I had updated the request.Headers.To to the URI of the service B. But this method never gets called. I have also attached an EndPointBehavior to it.

My sample code below. I am using .Net 4.5.

SimpleMessageInspector class

public class SimpleMessageInspector: IClientMessageInspector
{
  public object BeforeSendRequest(request, channel) 
  {
     request.Headers.To = new Uri("http://localhost:8087/B");
  }
}

App.Config ...

<services>
   <service name="A" behaviorConfiguration="AServiceEndpointBehavior">
      <endpoint ... 
      <endpoint ...
      <host>
         <baseAddresses>
           <add baseAddress="http://localhost:8083/A">
         </baseAddresses> 
      </host>
    </service>
<services>
<behaviors>
   <endpointBehaviors>
      <behavior name="AServiceEndpointBehavior">
         <simpleBehaviorExtension/>
      </behavior>
   </endpointBehaviors> 
   <serviceBehaviors>
      <behavior>
         <serviceMetadata httpGetEnabled="True"/>
         <serviceDebug includeExceptionDetailsInFaults="False"/>
      </behavior>
   </serviceBehaviors> 
</behaviors>
<extensions>
  <behaviorExtensions>
   <add name="simpleBehaviorExtension" type="A.SimpleBehaviorExtensionElement, A" />
  </behaviorExtensions>
</extensions>

... 

In the end, the service A is never calling the service B. Where am I going wrong here? Your help is appreciated.

By the way, there are few questions here in SO, but nothing seemed to work for my case.