How to deal with my manager?

Hello friends. I work in a reputed MNC bank.its been 6 months that i joined this company and i love my work.i have an issue with my manager (who is a female).myself and my colleague manage all the work, and she(assistant manager) takes all the credit.iam very much frustrated with this situation.though it is a corporate company, she(assistant manager) behaves as if we are her servant maids.yelling and making fun of us all the time. My colleague even complained about her(assistant manager) to her boss(My manager).they even gave her some kind of a warning . she was ok for some days. But now she is back to herself again.she doesnt listen when we give her any work updates, and when she messes up in the meeting, she (assistant manager) blames us for that.if i confront her directly, then it will only worsen the situation. iam not sure if talking to my manager would be of any use...need advice. i want to fix this situation. i love my work and dont want to leave the company for this stupid lady...Pls Help...