Device lackluster after repairs

The very first repair of my Samsung Galaxy Note 4 was due to an issue with the camera module, so I took it to get repaired at the Gateway Vodacom store. The repair time was excellent and I appreciated the turn around time. However they explained that while replacing the camera module the screen was damaged and needed to be replaced, I didn't mind this as problems happen and I was understanding(had to get an new screen protector). However I noticed that dust was starting to build up under the front facing camera and that my selfies started to look cloudy and overexposed. A couple months later the screen died on me and it started artifacting with green and purple lines followed by a black screen. I took it back to get it replaced, again with a timeously manner. But the problem still persists with dust somehow getting into the front facing camera, I wonder if the screen might die again because of this? Why now must i sit with a phone that is not in a perfectly working order (a device that is supposed to work with no flaws or issues). If the first screen was not broken then there would not have been an issue to begin with, with dust. So my question is now what do I do?