Since hoodoo got mentioned I’ll chime in. You could also create a vinegar jar to cause conflict with the colleague and her boss and possibly het her fired, if you have access to any of their personal effects ( buisiness cards, used chewing gum etc.) add this along with some vinegar, red pepper to inflame the situation, hair of a cat and dog, allum to silence their ability to communicate, poppy seeds to add confusion. If you know of any food allergies they have that can be thrown in as well to help sicken them to each other. Almost forgot 9 needles, nails or a piece of briar with 9 thorns.
Place each item in the jar and state your intent for example with the cat/dog hair state may insert names fight like cats and dogs. When you’ve added all the ingriedients pour the vinegar over the items and state as this vinegar is sour so your collegues relationship with her boss sour. Now shake the living shit out of that jar while thinking of all the pain this person has caused you. Imagine them inside that jar getting mixed with all those things you added.
You can either burn a black candle on top of it on each Tuesday and Saturday or you can burn a black candle next to it after shaking it up on those days. Burn a white candle for yourself in a separate part of the house and take a cleansing bath afterwards at the very least a salt bath, a hyssop bath would be preferable.
I have used bottle spells in the past with good results. Hope it helps and good luck.