Hi R,
It's a pity that people don't call you back when they say they will. Having said that, at least two dealer representatives couldn't resolve your problem without actually looking at the car, so it's probably a fair bet that the third one wouldn't have been very useful, anyway.
In such cases, one really does need to bring the car back to the dealership. If you don't need your car for the day, just turn up unannounced one weekday morning before 9:00, and ask for someone to look at the problem. I'm sure they won't mind. There can't be that many parts that make up a storage compartment, so it shouldn't take long for them to identify the problem while you wait. However, just in case it takes some time ...
If you do need a car during the day, you'll need to book in advance. The good thing about Lexus of Chatswood is that, even for minor problems, they will loan you a car for the day if they have one (and they have the biggest loan car fleet in Sydney).
But let's manage expectations: in the worst case, they will identify the problem, but they will need to order the replacement part, and you'll need to come back again to get the part fitted. That's just a part of any car owner's life, regardless of the marque or dealership.