supected theft of phone by staff member

I went to pay my account at the Wesgate Mall Mr Price and forgot my phone on top of the counter after payment. I quickly remembered within 5 minutes and went back to the store to retrieve it but was surprised to get there and found that the till I was paying at has been closed and the lady who helped me was now working at the back . What also surprised me was the fact that there was very long ques as the store was very busy for it was month end and the lady had decided to close the till. Like I said it happened within 5 minutes. I tried to ask her if she did not see my phone and she gave me a different pouch to mislead me saying that's what she found on the counter. I immediately asked the security if there are no cameras so that I can view the footage but she said there was none. I am suspecting her because when I came back she remembered me very well and said to me she had helped two people after me . I was so surprised that she remembered me. How can such a big store or company not have cameras for such incindences. why did they not follow the procedures set in case of theft is very surprising as I believe that they are suppose to close the shop and search whoever inside the sho