I think the issue here is the trespass and the damage of the OP’s garden. Often zero lot walls will have an easement for support and maintenance which resolves these…

no, that is not entirely correct
the neighbour needs to prove maintenance is required
the neighbour needs to prove maintenance cannot be done without access
just because neighbour wants it done immediately, i…

they have to maintain the wall
but they are not allowed on neighbours property
they must ask for permission, and if permission is denied
they must take legal action to request permission
which op…

no right to enter, it is trespass, this is why you don’t build to the boundary unless you have a zero maintenance wall

You neighbour has trespassed and damaged / stolen your property despite your assurance you would trim the the plant. In the interest of promoting a mutually respectful relationship in the…