Welcome to the Bunnings Workshop community. It's wonderful to have you join us, and thank you for sharing your question about caterpillars on your tomatoes.
Thank you for telling us that you've used Mavrik and Tomato Dust. Those two products alone should have stopped those caterpillars. Would it be possible for you to please take a picture of your plant and of the caterpillars? It is a bit of a mystery to me that the insecticide did not work. The only thing that comes to mind is that you have a very large infestation and no amount of insecticide will be sufficient to kill them all.
Can you please tell us how many days have you been spraying and when did you apply the tomato dust? Any other information you can tell us about when the caterpillars showed up would be helpful.
Let me tag our experienced members @Noelle and @Adam_W for their recommendations.
If you have any other questions we can help with, please let us know.