namespace Export
{
    public class XeroExport: ApiWrapper
    {
        public void ExcelExport()
        {
            DateTime startDate = DateTime.ParseExact(ConfigurationManager.AppSettings["PeriodStart"], "yyyy-MM-dd HH:mm:ss,fff", System.Globalization.CultureInfo.InvariantCulture);
            DateTime endDate = DateTime.ParseExact(ConfigurationManager.AppSettings["PeriodEnd"], "yyyy-MM-dd HH:mm:ss,fff", System.Globalization.CultureInfo.InvariantCulture);
            Call_BalanceSheet(startDate, endDate);
        }
        private List<InvoiceTableRow> converZInvouice(Invoice invoice)
        {
        }
        private String convertInvoiceToString(Invoice invoice)
        {
        }
        private void saveInvoices(string filename, List<Invoice> invoices)
        {
        }
        private void GetInvoices()
        {
        }
        private int GetTotalInvoiceCount()
        {
        }
        private int GetTotalContactCount()
        {
        }
        private int GetTotalJournalCount()
        {
        }
        public int CheckReportStatus(string ReportName)
        {
            ...  
            return ReportStatus;
        }
        private void Call_BalanceSheet(DateTime periodStart, DateTime periodEnd)
        {
            int reportStatus = CheckReportStatus("Balance Sheet");
            if (reportStatus == 1)
            {
                 ...
                 Insert_BalanceSheet(monthStartDate, monthEndDate, reportDate);
                 ...
            }
        }
        private void Insert_BalanceSheet(DateTime periodStart, DateTime periodEnd, DateTime runDate)
        {
            ...   
            var pal = Api.Reports.BalanceSheet(periodStart, null, null, false, null, null, null);
        }
    }
}

using System;
using System.Configuration;
using System.Data.SqlClient;
using System.Data;
using Xero.Api.Example.MVC.Helpers;

namespace Export
{

    public class BalanceSheet
    {
        private void Call_BalanceSheet(DateTime periodStart, DateTime periodEnd)
        {
            int reportStatus = CheckReportStatus("Balance Sheet");
            if (reportStatus == 1)
            {
               ... 
               Insert_BalanceSheet(monthStartDate, monthEndDate, reportDate);
            }
        }
        private void Insert_BalanceSheet(DateTime periodStart, DateTime periodEnd, DateTime runDate)
        {
             ....
             var pal = Api.Reports.BalanceSheet(periodStart, null, null, false, null, null, null);
        }
    }

}