Bad Service

On the 4th of August 2017 I booked much cellphone unit in for repairs at Samsung Stores 14Avenue as it the screen was damaged. I was told it will take 4-5 working days to be fixed. On the 4th day I received a call from one of the agents requesting the pattern or pin number as they say they could not unlock the unit which I did. I then went into the store four days after a call for pattern to enquire if it has been fixed and was told by one of the agents in the store which is 4th Avenue that the unit was taken in for repairs in Sandton and I will receive it on Monday. On the 14 of August I went again into the store and was told that the unit was not ready but I will receive a call within two days to collect my cellphone. I haven't heard anything from Samsung since and and when I call in I'm being taken from pillar to post. Please assist.