Parsing XML parameters in SSRS

Hello, 

I have a requirement where I need to pass the credentials along with the input parameters to the web service I am calling. Steps I follower :

1. Created a  DataSource of Type XML and specified service URL in connection string. 
2. Created a DataSet and used above datasource.
3. created following query to pass credential parameters
   

<Query><Method Namespace="http://guidewire.com/cig/bc/external/billingSummary/producer/ProducerBillingSummaryAPIExt" Name="FunctionName" ><Parameters><Parameter Name="username"><DefaultValue>User1</DefaultValue></Parameter><Parameter Name="password"><DefaultValue>Password1</DefaultValue></Parameter></Parameters></Method>
<SoapAction>http://serverName/bc/ws/cig/bc/external/billingSummary/producer/ProducerBillingSummaryAPIExt</SoapAction><ElementPath IgnoreNamespaces="True">*</ElementPath></Query>

But this is erroring out and I am not even able to hit the Web Service. Following is my SOAP request XML which is working fine in SOAP UI. 

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:soap="http://guidewire.com/ws/soapheaders" xmlns:prod="http://guidewire.com/cig/bc/external/billingSummary/producer/ProducerBillingSummaryAPIExt"><soapenv:Header><soap:locale>en_US</soap:locale><soap:authentication><soap:username>User1</soap:username><soap:password>Password1</soap:password></soap:authentication></soapenv:Header><soapenv:Body><prod:Function1><prod:producerCodes><prod:Entry>10030</prod:Entry><prod:Entry>10130</prod:Entry><prod:Entry>10230</prod:Entry></prod:producerCodes><prod:startDate>2014-09-24T09:30:10-06:00</prod:startDate><prod:endDate>2018-09-24T09:30:10-06:00</prod:endDate></prod:Function1></soapenv:Body></soapenv:Envelope>

Could anyone please help me to send the required parameter to call the web service?

Thanks in advance,
Puneet Sharma