I'm having trouble doing "voltas" in samba. My teacher keeps yelling at me since I keep twisting my hips... any suggestions...

Hi,
Change your teacher! They only yell when they don't know how to correct a fault.

Go to the videos on this web-site. On the opening page you will see Samba. Voltas are there . I've just been looking at them. Have a look how the left heel is high and stays at that height all through when moving to the left.If your teacher has n't told you, make your steps small. Its not a race. To get the correct movement of the hips to the front and back and not to the side is a bit difficult. If you find this hard to do you are not alone. In fact the majority don't even know it exists.Bit more advice. Learn what a Latin Cross is. This is your foot position on the first step heel to toe. With your heel high move your left foot, that's the one that travels. The other catches up. Everything should be small. But again , go to the Video.