Hi Suresh,
That seems a bit odd that they cannot change it. Especially if it is invoked via client side scripting, as you said that they can see the trace in the browser.
Read the following which explains HTTP binding of a SOAP request.
http://www.w3schools.com/webservices/ws_soap_httpbinding.asp
As I said before as they are not providing the correct content type, the server rejects the request. I also said in my original post that the content type should probably be set to "text/xml" but it should be "application/soap+xml", so apologies for that.
The server cannot accept anything other than this content type as SOAP is always in this format. From a security point of view, it does not make sense to try and change it, even if it were possible.
Cheers,
Katan