In answer to the coke post.
In the book it said that a can of coke emptied into the bog and left overnight would get rid of limescale, haven't tried it yet.
Had one today, went and got dishwasher tabs and put one into the bowl and 20 mins later gone, excellent.
Put it into the other one, no effect, now left 3 in there overnight, keep you posted
Regards
Martin