Can I block a Standing Order payment into my account?

Flobberchops

The receiving bank will have minimal information about the origin of the funds, at least at the branch level. There *might* be a reference if the sender chose to use one.

Surely just ask your neighbours to check their statement, that should soon clear up whether they are sending you money? If they decline to do so, or it turns out it's not them, then enjoy the free money (by which I mean enjoy any interest it earns you, if it's a genuine error it could be recalled or demanded at any time, which is a pain in the backside).