In the header of Web.config file.
Be sure that begin with:
It Appear that the response is trying to match with your encoding wrote in your App/webb.
please review if your project is over ISO-8859-1 encoding or UTF-8
Or
check if the WSDL show you this encoding
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http://localhost:60789/AppService.asmx?WSDL[
^]
Other way could be that the Web service App.. is not Configured Properly