Very poor service!!!

I have a Samsung Galaxy S4 mini cellphone, that I got on contract on the 1/2/2015. The phone started giving me trouble in November 2015. I gave my phone in at Vodacom Repairs Potchefstroom, at West Acres Shopping Centre, on the 4/1/2016, with the reported fault being: Operating system hanging and system errors. I got my phone back on the 6/1/2016. Almost immediately my phone started doing exactly the same thing. I took it back to the same shop on the 15/1/2016, the same reported fault. When I got it back, the same thing happened. I took it back on the 21/1/2016. The reported fault was error - touch wiz failed. When I got it back, the problem didn't reappear for almost 3 months, but my phone is broken again!!!! I gave it in at Vodacom Repairs on the 22/4/2016, and I haven't gotten it back yet. I know the solution is not going to last, it never has before!!!! The staff at the shop is really unfriendly and unhelpful. It is as if I have to be thankful that I get to have my phone wiped, losing all my numbers, pics etc. I want my phone fixed permanently or I want a new phone!! Enough is enough!!!!!