If I were you, I’d ask them to connect your router directly to your laptop as you said you want to get rid of the desktop.
The computer may have other things wrong with it besides needing a cleaning. You are afraid of the thing you think you need the most. Why not get to know it a little. Take a picture of the ports on the back of the computer, or make a schematic drawing. Get to know the geeks a little. People aren’t that unfriendly. Also, you are spending all your time worrying about and talking about your feelings when you could simply let them rise and fall as feelings will do. You’re afraid of your own feelings. This is snowballing and you are caught in a vicious cycle. The more you talk, the more you dwell on your feelings, the more you dwell on your feelings, the more you work yourself up. Change your thinking about your feelings. That is the only thing you can do at this point. Then the feelings might calm down.