Poor Service

Very Disappointed with me S6 Edge I can not get signal or Data connections. It drops this connection or takes forever to connect and times out. I have taken it in to the Samsung centers 3 times in the past month and it still has not been resolved. They claim to have reloaded the software but when i received the phone is was the same as when i gave it in. . How to i over come this issues. My contract cost me R1000 and now i am suck with a phone that does not work so well.