If someone hi-jacks your e-mail accounts and has your e-mail forwarded to their account how can I report it?

Someone who has a Yahoo account (Goldenfish101@Yahoo.com) got into my e-mail accounts both at Yahoo and Hotmail and not only was having my e-mail forwarded to their account but also sent many people on my contact list a request using my name and saying that I was in Spain and needed money, asking them to send $2500 asap. I know this is a scam that has been used before, but I think that these people should be made accountable for disrupting other people's lives and property as well as mine. They should be blocked from having any e-mail accounts because they are dishonest. I am a grandmother who is disabled and almost 77 and I do not appreciate this kind of thievery attempt. I only managed to get their account name because my son was trying to help me fix my computer and when I could finally look at the e-mail content on Hotmail, it told me that this "Goldenfish101@Yahoo.com" was importing MY e-mail to their account. Please let me know how I can get these e-mail thieves to stop what they are doing. I know that if they have done it to me, they have probably done it to others.