Accessible toilets that don’t lock

Accessible toilets in stockton on tees shopping centre don’t lock from inside. And the “engaged” sign outside doesn’t move to show the toilet is in use. Meaning disabled people do not have privacy and dignity when using this facility I informed centre management who said the toilets would be improved as part of ongoing works. So they will not be improved until then. Four months after I reported it, the problem still remains. Its solely a case of fitting a new handle locking system. Why is this too much to ask? Why should this take 4 months plus?