Frustration with bad service

It has been 3 weeks now where I booked my Samsung phone in for repairs. Like I drive to the store to collect my phone, because they phoned me to tell me it is fixed. Then I luckily tested the phone to discover it doesn't work, I drove all the way from South of Johannesburg to Rivonia. It is nonsense, plus they told me they will get a new phone for me or replacement. Today I phoned the manager just for him to say it isn't possible as Samsung itself says my phone has dents which I haven't seen by the way...it is just bad service!!!!!!!!!!!!!!!!!!!!!!!!!