Should the flue from my Ariston A30 MFFi be dripping? (and other questions)?

I have recently had an Ariston Combi A30 MFFi installed. The flue is located a good height above my downstairs neighbour's front door. However, it has been spurting water out on top of her when she leaves the house, which she's not at all happy about! The installers have been back twice - they put something under the flue to raise it, which initially did the trick, but now the problem has started up again. Before I push them for further action, I want to be sure that this is not supposed to happen. I understand about the plume, and that's OK, but drips and spurts of water? Also, is this definitely an installation problem, or should I be speaking to Ariston?

In connection with the same boiler, can anybody explain the "Temperature holding function" to me? The boiler regularly comes on even when taps are not run and the heating is supposed to be off, I assume because of that function. Is it neccesary? - seems like a waste of energy. If it's not necessary, how do I stop it?

Finally, the instruction booklet talks about the room thermostat, but i'm not aware of having a room thermostat unless it is inside the boiler, which would seem strange. Do I need one? Some of my radiators have thermostatic valves. Will these work with this new boiler? How can they work when there is no form of communication between them and the boiler?

Apologies for the stupid questions, but I don't know much about boilers!!