//Load DichVu Theo HoaDonID | PhongID
        public void DichVu_Load(int _HoaDonID, int _PhongID)
        {
            LoadingPanel.IsBusy = true;

            DichVuClient = new DichVuSVCClient();
            DichVuClient.DichVu_GetItemsCompleted += new EventHandler<DichVu_GetItemsCompletedEventArgs>(DichVuClient_DichVu_GetItemsCompleted);
            DichVuClient.DichVu_GetItemsAsync();
            cbxDichVu.SelectedIndex = 0;
            rdpNgaySuDung.SelectedDate = DateTime.Now.Date;

            HoaDonID = _HoaDonID;
            PhongID = _PhongID;

            HoaDonDichVuClient = new HoaDonDichVuSVCClient();
            HoaDonDichVuClient.HoaDonDichVu_GetItemsByIDCompleted += new EventHandler<HoaDonDichVu_GetItemsByIDCompletedEventArgs>(HoaDonDichVuClient_HoaDonDichVu_GetItemsByIDCompleted);
            HoaDonDichVuClient.HoaDonDichVu_GetItemsByIDAsync(HoaDonID, PhongID);
        }
        void HoaDonDichVuClient_HoaDonDichVu_AddCompleted(object sender, System.ComponentModel.AsyncCompletedEventArgs e)
        {
            LoadingPanel.IsBusy = true;
            cbxDichVu.SelectedIndex = 0;

            txtSoLuong.Text = String.Empty;
            rdpNgaySuDung.SelectedDate = DateTime.Now.Date;

            HoaDonDichVuClient = new HoaDonDichVuSVCClient();
            HoaDonDichVuClient.HoaDonDichVu_GetItemsByIDCompleted += new EventHandler<HoaDonDichVu_GetItemsByIDCompletedEventArgs>(HoaDonDichVuClient_HoaDonDichVu_GetItemsByIDCompleted);
            HoaDonDichVuClient.HoaDonDichVu_GetItemsByIDAsync(HoaDonID, PhongID);
        }