That's the question I asked her to which only you've replied - is the situation REALLY as bad as we all know it to be that she's intervening in the city's competence (she wrote: the 'Constitution prevents spheres of government encroaching on the mandates of other spheres, except when there has been a complete breakdown of service delivery')? 
But neither her article nor city (De Lille: 'a well-run city does not run out of water' and it's not a crisis) has stated there's a breakdown of services. As far as they're concerned, it's hunky-dory. Therefore, if that's the case, Zille has no business, and is violating the constitution (again), responding to these 'questions' - if they were sent to her at all and are not hypothetical and generic - and not handing them to De Lille as she ought to. QED. As I said, the constitution permits one or the other, not both.
Teresa, a big fan of Zille, agrees with you. Teresa, you're backing the wrong horse, let's call it 'Colonial' on her last race/legs.