I dealt with a number of cases where a responsible person would seek advice about a neighbour blocking off an agreed MOE through their property (often where I worked this involved a MOE from the roof and through the neighbour's identical over height single staircase building).
I used to explain to the complainant that an Inspecting Officer would attend if the RP really wanted one, but as Kurnal has said, we may issue a notice or insist on a voluntary agreement (akin to a voluntary prohibition notice) as we had very little powers in such disputes to force the neighbour to do anything. I would advise that the consult a solicitor in the first instance.
Some RPs just didn't understand my advice or were just so angry and insisted a IO attended. I hated these jobs as there were no winners when on a number of occasions, I informed RPs that they would not be able to use the top floor(s) until the MOE situation was fixed