What can I say...
If your number is so important to you, don't jump into the first MVNO offer you see.
At the very least, Eight offers free 88-day trial SIM without obligation, though latest offer is ending this month and I hope they don't offer some more until they've ironed out all those problems due to overwhelming response.
Try it to know if it meets all your needs and expectations first. Go check out their FAQ. Lots of useful information there.
There are quite a number of MVNOs, don't expect one to have everything out there. Otherwise MNOs eat grass...