The first thing you should do is ignore all his threats and block his email address along with his Whatsapp number. Make yourself unsearchable on the app. That way the harassment will end /stop. They can only threaten you if they can reach you.
Next, continue this thread by helping other students. Make it clear, by naming names, which company you hired from this forum since you claim to have found the company / writer via this site. That way the victimization of students coming across them here can be prevented.
Finally, stop worrying about the threats. Although there are some instances when they do try to contact the school officers, these actions often result in inaction from the school since the schoolk are conscious of these tactics.
Let this be a lesson to all concerned. Never hire a company or freelance writer to take exams for you. They will just Google the answers anyway which is something you can do yourself. If you are still getting a D anyway, you may as well save the money.
Consider yourself lucky that your school does not do an lP trace when you log in for exams. Had you been l P traced, the school itself would have immediately known that you cheated, locked you out of the test, and had the strongest evidence to immediately expel you from school.