Code to update data source connection string and stored credentials in MOSS web part having SSRS 2012 as service application?

Using VS2012 I created an empty MOSS project and added a web part to it. Sand-box soln. and Feature scope is Site(Sitecollection). How to reference SSRS2012 as service application in sharepoint project so that i can update the connection string and stored credentials(user-id and password).

Why? We migrated from MOSS2007-SSRS2005 to MOSS2013-SSRS2012. So now in development environment we want to point to our new database server with new user-id and password.

My following code to reference name property works but I need a mechanisn to reference data source:

SPWeb web = SPContext.Current.Web;           
SPList dataSrcList = web.GetList("http://abc:11111/xyz/Data%20Connections/Forms/AllItems.aspx");           
lblItemList.Text = "";
SPListItemCollection items = dataSrcList.Items;
for (int i = 0; i < items.Count; i++)
{
SPListItem listItem = items[i];
lblItemList.Text += "<BR>Name: " + listItem["Name"]; //works
//lblItemList.Text += "<BR>Connection string: " + listItem["Connection string"];
//lblItemList["Connection string"] = "abc";           
//lblItemList.Update();
}