it looks problem with encoding, check with Web service team what type of response they are providing like encoding,character set format,according to that u need to set encoding in SOAP channel.
couple of discussion avaiable on net, search..
http://social.msdn.microsoft.com/Forums/en-US/wcf/thread/f29cd9c8-3c89-43d2-92ae-d2a270ab86b9/