Breach of contract

took my phone to Edgar's connect Tsakane mall or repairs (screen repairs) and I was phoned after a month to come and fetch my phone but I arrived to the store to our surprise the screen was fixed but but when you switch it the screen remained blank so the phone was returned to Finite and it was fixed. Two week after I received my phone I started noticing that it would minimise application while I'm busy it and it even went blank at one time that's when I decided to take it back to store seeing I had a three months warranty

To my surprise when I explained to the gentleman(who did even introduce himself and had no name tag on) who was called to assist me ,he blankly told me that he does not see anything wrong with the phone and he won't take it back.

So what I want to know know is this want I get for taking an insurance with Edgars and now that my screen cracked again does this mean I'll be stuck with this technical problems that occurred after my phone was fixed by Finite?? Does the warranty still apply as per T&C's