public SettingsControlViewModel(IBillingManager bill)
 {
     BuyServiceCommand = new RelayCommand(args =>
     {
         OnClose();
         bill.NavigateToBuyServiceWizard();
     });
 }
 public ExpiryPopupViewModel(IBillingManager billing, DateTime time)
 {
     Time            = time;
     _timer.Elapsed += _timer_Tick;
     BuyCommand      = new RelayCommand(args =>
     {
         Close();
         billing.NavigateToBuyServiceWizard();
     });
 }