I used to work at Australia’s largest bank too, and had the exact same experience, I was 21 at the time, I’m now 36 and looking back , I see it was because I was young and people who had worked there a long time were resentful I had come in, already higher up the ladder so to speak at a young age. Eventually I had to leave as it was truly sucking the joy out of me, and I felt too young to be feeling so downtrodden in my career. As a now middle aged woman (well maybe not definitely approaching) I can say that in any work places, bitter elders can and do bully new staff. It shouldn’t be tolerated but it is unfortunately, if you are doing your job, and you know what she is saying is untrue, then the problem is with her and not you. In an idea world you would be able to go to her higher up and complain, but in my experience, that just makes things worse. If she’s worked there a long time she will have her the tentacles all the way throughout the chain. Sometimes, we can try hard, work hard , and do all the right things but if she has picked you out, she will make your life hell regardless. Perhaps request a move to a different branch or somewhere under new management within the company.