Headaches

I own a Samsung Note 4 cellular phone which started to malfunction while still within the 1 yr guaranty period. The purchase date was the 01-05-2015 at Cell C Menlyn. The faulty phone (Proximity sensor not working, phone not charging, apps opening randomly) was booked in at Smartlab Menlyn on the 17th of March 2016 for repairs. I received the phone back 20 days later on the 6th of April, with a loose screen which was repaired there on the spot. Upon inserting my sim card I discovered that it couldn't connect to any cellular network and as result the phone was booked in for a second time on the same day. I received it back on the 19th only to be bugged again by the non responsive proximity sensor problem and as result took the phone back to them on the 27th. This is bad and it seems as if they are reluctant to replace the phone even though this being the 3rd time it went in for repairs, which it seems they can't do as the problem persists. I want the phone to be replaced and not repaired and am not impressed with the service at all.