Shared pathway? What are my rights?

I live in a housing association home that I do not own but lived here for 10 years. My neighbours have recently moved in and are creating a wall which will block my gate. They did ask permission and we declined yet they are proceeding. When I asked the housing association they let me know its a shared driveway and they will do a site visit and go from there.

Just to make this simpler to understand, both properties front gardens are seperated by a fence at the minute but it isn't fenced all the way as that would block my gate (https://imgur.com/a/36hlnev)

What can I do?