Repairs and Servicing Complaint

I purchased a Samsung J1 smartphone through a cellular provider approximately 4 months ago. Ever since I received the phone, it has given me nothing but issues. I specifically chose a simple model, as I didn't want anything complicated. Absolutely everything has gone wrong with this phone-keypad issues, volume issues, inability to download from play store, no touch response, no connection/slow connection to the internet, losing images, watsapp messages not being sent/received, the phone using massive amounts of data disproportionate to what I use it for, screen freezing, over-heating, switching to power saving mode and not coming out of it, disabling apps randomly etc. <br> I have taken the phone to the Samsung repair centre, and have sent it in for repairs 3 times. Apparently the motherboard and the screen have been replaced, but there are still issues. I cannot understand why my phone was not replaced immediately and why, if it has been repaired, it continues to develop issues. <br> On top of that, every time something goes wrong I have to go back to the store again, and every time it is sent for repairs, it takes up to 2 weeks for my phone to be returned.<br> Shocking service.