Unsatisfactory repair

My phone fell in water 3 months ago and naturally I took it to Samsung in century city so it could get fixed. It took about a month and half just to get an invoice and when we finally got one they took another month and a half to get the phone fixed. I just got my phone back yesterday and today was the first time using it and the first thing I noticed is a water stain at the top left corner of the screen and not only that but the home button and power button are still not working which gives me the impression that this phone was not actually fixed and what they did was give me a product that was temporarily fixed. One can imagine my anger considering the fact that I waited 3 months to get the phone fixed, I paid R2 500 for the repairs and the phone is still not fixed when they told me the repairs cost so much because the phone will be new, which obviously is not the case since it has the same damages before I gave it in. The phone is a Samsung J5 prime which cost R2 999 and the repairs as mentioned above was R2 500 which is practically close to the cost of the phone so I'm trying to understand how the phone has these problems when firstly the repairs were almost the same amount as the phone itself and secondly they said it would be practically new. Please guys I've waited long enough to get my phone to function properly only to get it back to the way it was and I refuse to pay more money to Samsung to fix this phone again cause clearly it was not worth it but I would really appreciate a refund or at least get my money's worth cause this is not fair especially to one of your customers. What can be done??