Unable to clear remote notifications on iOS

Using Unity 3.5.5 we've registered and then recieved a number of remote Alert notifications.

However we've been unable to programatically remove them from the device using the documented method:

 NotificationServices.ClearRemoteNotifications();

It appears this has no effect on the status of the notifications.

Can anyone confirm whether this is a bug in the notification services functionality and/or offer a workaround so we can clear them from the device.

Thanks in advance.

Evan