Item not found after 4 days

On Friday I went to go take out my S3 Samsung which I had put in on a 30day contract, they were not able to find my phone that day, made me come back the following day and still haven't found it! Today is Monday, late Monday, the day they told me they would contact me telling me to come get my phone....still nothing?????? Will I even be getting my item back or how does this company work, this is such an inconvenience