hi.. I am in a exactly same situation like you. I paid expertacademichelp for my assignment as I was so struggling and didn't have enough time to do. But as my own gut feeling, I didn't trust them much so I did the assignment by myself and submitted on time. Then they sent my order after 3 days of my deadline so obviously I didn't use or submit their work. But 2 weeks later, they started contacting me saying that I have been under investigation for copyright issues and if I pay for copyright certificate, everything will be fine. I just ignored them but today they emailed me again saying they gonna contact my university(they know which uni I'm studying so that's what I am worried) about it and kept threatening me. I and so emotionally stressed and don't know what to do. I should not have done that in the first place. I want to ignore them but I am scared that they gonna keep blackmailing and threatening me. I know myself clearly that I didn't use or submit their work but what if they actually contact my university? I don't want this to get any bigger.