There have been many scientific studies of every level of astrology. James Randi has covered several of them in his books. Astrology not only doesn't work but has no consistent practice. That means as soon as one astrologer is proved a fraud, another one pops up and says they have a better understand of astrology. When their techniques don't work, yet another pops up and says their techniques work. And so it goes.
If you know of any astrologers who are successful, by all means send them to James Randi. He will pay them a million dollars if they can prove their abilities work under scientific conditions.