I think it is a safe bet that your camera is not faulty. Your issue is with learning the technique for Live View focus. Live View contrast detect focus is slightly more accurate and more consistent than the phase detect focus normally used. The difference is relatively small with the newest cameras.
There are two techniques for using Live View focus. One is to magnify the image and manually focus. This is the technique used for macro where there are options on exactly where you want to focus.
The other approach is to use Live View mode, position the AF sensor where it is needed, and then activate focus using either the back button or the shutter. You probably will need to use a tripod to make sure the focus is on the right subject. There is a lot of precision in the camera, so if you miss focus you will certainly see it.
One variation on the use of Live View is to simply use the LCD screen instead of the viewfinder. This can provide some unique angles for photos without contortions. Again - you would use the desired AF mode and let the camera focus. This technique works for Dynamic AF with a group of sensors.
Contrast detect focus is accurate - it just is not as fast as phase detect AF. So for moving subjects it may not work as well as phase detect.