I agree with all the above - last time I bought any, thick bleach is about £1, and cheapo bleach starts at 30p. Worst case, if they think they need to leave it to PROVE there's a damp problem, why not photograph it, THEN scrub it off? Weird, but having lived in council accomodation I agree that is usually the attitude - let the council/state fix it. (Am I the only person who thought the subject line was GEOGRAPHIC in nature, thus meaning that when I read "One wall of the room is taken up with a huge black furry shape," I had a very brief vision of a gorilla?)