Agreed they are FA's, ie Flight Attendants, so their duties are to attend to the needs of their customers. I and quite sure
that in their conditions of employment, or job spec or manual it is clear that providing timely food and drink I their responsibility
either proactively or on demand, or both.

The Call Button is simply a way to call the FA, no harm in going to the galley also, however be careful hanging around, friends of mine say they get fed up with
over friendly chatters how get in the way, and stop the crew enjoying their times to relax and chat.

Of course just as in any customer and service situation , one should treat people with respect and courtesy.