I am younger than this person, but I am more senior than her. Her job is partly to assist me in my job and to do work from others.
There is one specific type of work that she organises and I do. My own manager has said that this work comes last as it’s never urgent.
I have been busy with my own work and work for my manager. The less senior colleague has been chasing me for the very non urgent work. They have now started coming to my office and demanding I do their work now. It does not need to be done now and my manager agrees. Yet she comes whenever my manager is away to try and bully me into doing it when I am already stressed and busy.
Today I lost my cool and sternly told her that there is an order of priority for work and hers comes last.