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Hello I will assist you today.
With regards ***** ***** plants, ANY plant, branch etc that grows onto or crosses onto a your property, can be legally cut or trimmed back to the point of the boundary. Anything cut or trimmed MUST then be offered back to the owner of the plant or tree. You cannot just throw it back across.
Next, as far as the wall is concerned, if the wall is 100% built on your land and in no way encroaches on their land, then they have NO legal right to interfere with your wall, either painting it, attaching items to it, or in any other way interfere with it. It they do, you can insist that they stop and make good any damage. Failure to do so would allow you to see a legal remedy against them.