Poor workmanship and NO quality testing

I sent in my Samsung Galaxy Note 2014 eddition for a warranty claim on the screen that was faulty, after waiting for 3 weeks with no response or follow up i received my tablet back, only to realize that none of the functions on the front was working (camera, light sensor). I took my tablet back to the Samsung care center in The Kolonade, The technician opened the tablet in front of me and we found that the parts was not even fitted inside my tablet. I find this extremely pathetic, how do they repair a product and send it back without doing proper quality checks. I have been struggling to do business without my tablet and every time I enquir there is no clear answer on how long I have to wait, I am getting impatient as I am losing business and money due to someone elses mistake.