Has your agent took the house off the market then? We have a offer on ours but I wont accept until the buyer has sold their's but I wouldn't take it off the market until exchange as buyer can think they can have you over (this has just happened to my 70 year old dad-buggers). The thing with estate agents they dont like to work hard (mind hide under his desk when he see's meha ha) for their money so you have to keep them on the ball they should be finding out what is going on not leaving you in limbo! Get them to keep the viewers coming so you can have something to fall back on if the buyers get greedy.
As for the neighbour cant you get an injunction to take the sign down?

if not go to Oz and rent out to a large family of illgal immigrants that will put him in his place ha ha. No sorry its not funny but if the neighbour let you sell he wouldn't have to worry about his bloody border.

Hope this gets sorted for you.
Good luck with house sales
Marge x
