I'm far from experienced, but if I was in your situation I'd certainly be demanding answers. If it's an issue with your progress you need to know exactly what it is so you can work on improving it. If it's not you, then you need to know what it is and what can be done to mitigate it.
If I get to 36 hours in and haven't solo'd I'll be very disappointed. I'm only 4.5 hours in but have taken off on my last two lessons so feel I'm making reasonable progress. Stalling tomorrow, which I'm not quite so keen about!!