Ist cyberpcexperts.com sicher?

About a year ago my computer was running slow. Somehow I they found me at a weak moment and I paid $400 for four years of service to take care of everything, security, malware, etc. They did make the computer run faster, but On May 15, 2015 they called my home and said I was having computer problems and someone was taking over my computer. They showed me all of this stuff on my computer, even said things have stopped running, very scary. Then they said that they could fix it for $799. I told them that I was not going to do that and I could not afford it then they said $599. Still I said no. They got very pushy, angry tone in their voice. I still said no. When I turned my computer back on all deck top icons were missing. This is my fault for using them the first time without checking them out. They had worked a great scare tactic out and kept saying that they were a Microsoft Office and worked for Microsoft.