The other month I brought my laptop into a shop for repair. I included the power supply and cable just in case he needed it, even though I figured if he wanted to test if it's working right there was probably more than enough energy in the battery, and somehow I had the feeling he'd lose my power supply. Sure enough, when I came to pick up my laptop weeks later, the power supply wasn't with it. I told him I gave him the power supply with it, and he denied it, telling me about the system he uses to make sure he keeps track of power supplies and anything else that belongs with a computer, and how there was no way I gave him the power supply or it would be there. I ended up having to order a replacement for $70, not even having any way to be sure of its quality, and having to wait another couple of weeks for it to arrive before I could use my laptop.