private void Btn_Add_Submit_Click(object sender, RoutedEventArgs e)
        {
            int serviceCount = App.listOfServices.Count;

            if (btnName == "Add")
            {
                var newService = new Servicesinfo
                {
                    ServiceId   = "S" + ++serviceCount,
                    ServiceType = Cbx_Serv_List.SelectedValue.ToString(),
                    Price       = Txt_Price.Text,
                    Description = Txt_Description.Text,
                    Location    = Txt_Location.Text,
                    PostedDate  = Dp_Date.Text,
                    PersonId    = App.loginPersonInfo.Email
                };

                foreach (var person in App.listOfPersons)
                {
                    if (person.Email == App.loginPersonInfo.Email)
                    {
                        person.Offered_services.Add(newService.ServiceId);
                        break;
                    }
                }
                App.listOfServices.Add(newService);
            }
            else
            {
                App.listOfServices.Where(S => S.ServiceId == selelctedService.ServiceId)
                .Select(S => { S.ServiceType = Cbx_Serv_List.SelectedValue.ToString(); S.Price = Txt_Price.Text; S.Location = Txt_Location.Text; S.Description = Txt_Description.Text; return(S); }).ToList();
            }

            Mystorage.WriteXML <ObservableCollection <Servicesinfo> >("Serviceinfo.xml", App.listOfServices);
            Mystorage.WriteXML <ObservableCollection <Personinfo_with_service_details> >("Personinfowithservicedetails.xml", App.listOfPersons);
            MessageBox.Show("Service Added Successfully....");
            OfferService.UpdateServiceList();
            this.Close();
        }