I am new to Integration Projects. I have an Apex class generated from the WSDL of a third party. I would like to utilize the methods of that Apex class and write a batch class that utilizes the response.
Here is the error that I received when testing the code below

Web service callout failed: WebService returned a SOAP Fault: System.Web.Services.Protocols.SoapException: Server was unable to process request. ---> System.NullReferenceException: Object reference not set to an instance of an object. at DataServices.a2zService.GetCustomSqlReport(XmlNode request) in D:\inetpub\wwwroot\027112\Partners.a2zinc.net\DataServices\App_Code\Public\a2zService.vb:line 176 --- End of inner exception stack trace --- faultcode=soap:Server faultactor=

Can someone help me on how I could test the response in Anonymous window? I can then use the same parameters in batch class as well
Here is the code that I tried executing anonymously

Request.request_element req = new request.request_element();
Dataservices.ServiceSoap service = new Dataservices.ServiceSoap();

Response.response_element res = service.GetReport(req);
system.debug('response'+res);

Here is my Apex class

public class Service {
    public class AuthenticationHeader {
        public String Key;
        public String UserName;
        public String Password;
        private String[] Key_type_info = new String[]{'Key','http://www.show.com/Services/Service/v1',null,'0','1','false'};
        private String[] UserName_type_info = new String[]{'UserName','http://www.show.com/Services/Service/v1',null,'0','1','false'};
        private String[] Password_type_info = new String[]{'Password','http://www.show.com/Services/Service/v1',null,'0','1','false'};
        private String[] apex_schema_type_info = new String[]{'http://www.show.com/Services/Service/v1','true','false'};
        private String[] field_order_type_info = new String[]{'Key','Source','UserName','Password','InstallName'};
    }
    public class ServiceSoap {
        public String endpoint_x = 'http://partners.inc.net/services/public/Service.asmx';
        public Map<String,String> inputHttpHeaders_x;
        public Map<String,String> outputHttpHeaders_x;
        public String clientCertName_x;
        public String clientCert_x;
        public String clientCertPasswd_x;
        public Integer timeout_x;
        public Service.AuthenticationHeader AuthenticationHeader;
        private String AuthenticationHeader_hns = 'AuthenticationHeader=http://www.show.com/Services/Service/v1';
        private String[] ns_map_type_info = new String[]{'http://www.show.com/Services/ReportRequest/v1', 'Request', 'http://www.show.com/Services/ReportResponse/v1', 'Response', 'http://www.show.com/Services/Service/v1', 'Service'};
        public Response.Response_element GetReport(Request.request_element request) {
            Request.DataService_element request_x = new Request.Service_element();

The Request class:

//Generated by wsdl2apex

public class Request {
    public class Service_element {
        public Request.request_element request;
        private String[] request_type_info = new String[]{'request','http://www.show.com/Services/ReportRequest/v1',null,'0','1','false'};
        private String[] apex_schema_type_info = new String[]{'http://www.show.com/Services/ReportRequest/v1','true','false'};
        private String[] field_order_type_info = new String[]{'request'};
    }
    public class request_element {
        private String[] apex_schema_type_info = new String[]{'http://www.show.com/Services/ReportRequest/v1','true','false'};
        private String[] field_order_type_info = new String[]{};
    }
}

Response Class:

/Generated by wsdl2apex

public class Response {
    public class Response_element {
        private String[] apex_schema_type_info = new String[]{'http://www.show.com/Services/ReportResponse/v1','true','false'};
        private String[] field_order_type_info = new String[]{};
    }
    public class Service_element {
        public Response.Response_element Response;
        private String[] Response_type_info = new String[]{'Response','http://www.show.com/Services/ReportResponse/v1',null,'0','1','false'};
        private String[] apex_schema_type_info = new String[]{'http://www.show.com/Services/ReportResponse/v1','true','false'};
        private String[] field_order_type_info = new String[]{'Response'};
    }
}

Here are the request parameters that I use to test in SOAP UI