Certified GKH Gardening Expert
Without pictures and a detailed description of its care, the temperature and watering habits, and the area that it is planted, it would be very difficult to give you any useful diagnosis without guessing. It could be a great number of issues.
Please include photos and the details listed above and I will be more than glad to help.
In the meantime, this article will give you information on th care of these: https://www.gardeningknowhow.com/ornamental/shrubs/broom-plants/how-to-plant-broom-shrubs.htm