Staff at kfc kolonnade stole my daughters phone

I went to kfc kolonnade on the 7th of July with my kids, my daughter forgot her phone there, I went back after 30 min and they told me the had not seen it, two weeks latet on the 20 July I logged on to find my device and the phone was tracked to the same kfc and it was connected to the kfc wifi, my sister went to the kfc and was not allowed into the office to view footage and was only given footage only showing us walking out the store, I decided to go to the store myself and the manager told me there was nothing more she could do and I should open a case with the police even though the phone showed it was still in the store, I called their head office and explained the situation and was told they would let the division manager investigate and call me. No one has gotten back to me.