// Dto class for object mapping to excel template
class ReportDto
{
    public string ParentItem { get; set; }
    public string Description { get; set; }
    public string Branch { get; set; }
    public IEnumerable<Record> Records { get; set; }
}

class Record
{
    public string ComponentItem { get; set; }
    public string Serial { get; set; }
    public string VendorName { get; set; }
    public string ProductName { get; set; }
    public string Location { get; set; }
}

// service class for writing excel document
public class ExcelServiceWriter
{
     private Service1 _srv1;
     // dependency inject from container
     public ExcelServiceWriter(Service1 srv1)
     {
         _srv1 = srv1;
         //....
     }

     // generate excel document via template
     // template path might be: \...\folder1\folder2\template.xlsx
     public void CreateExcelViaTemplate(IEnumerable<ReportDto> sheets, string saveAsPath, string templatePath)
     {
         foreach (var sheet in sheets)
         {
            using (var template = new XLTemplate(templatePath))
            {
                  template.AddVariable(sheet);
                  template.Generate();
                  template.Workbook.Worksheet(1).Rows().AdjustToContents();
                  template.SaveAs(saveAsPath);
            }
         }
     }

}