Hey Pendulum,

This is a very sensitive issue. I dont want you to loose your job, but at the same time, i dont want you to be exploited. It will be best if you can find another employer first, but it might be difficult. You can go talk to them and say that if you do not get the hrs and pay rate mentioned in H1B petition, you will file the WH-4. But, like you said, they might fire you. you can sue them for that, but you will be jobless. So, wait until you have some options. If you find another job, then you will be in stronger position to take actions. Dont rush into any decisions. Take your time, and take the best decision.

You may want to consult a lawyer to find out all your options.

Good Luck