I have found in my dealings with English Heritage you have to keep constantly phoning, e mailing and generally making a nuisance of yourself to get anything done!
I would be more than happy to cleanse this 'cursed' site and send any poor lingering souls on their way if necessary next time I am in Dover if access could be gained. Please note I would not do this as a psychic investigation, I am always respectful and it would be to merely to remove anything negative.