Refusing to pay claim for unrealistic reasons

I was cooking food and serving customers, I put my phone down in my kitchen ( a non public area)to take food to the customer as I always do as serving food with your cell phone is not professional, when I came back my phone was gone from the kitchen where only staff are allowed (my kitchen is 2m from the bar where food was served). My claim was rejected as it was \ left vulnerable for anyone to just come and take". I find this unacceptable as it is not a public place and insurance is paid for this specific reason. The lady told me that the phone was not on me when it was ****** and I left it exposed. Do they only cover claims if the phone is on you or you see it get ******? I now understand why lies are made to insurance companies as it is too easy to tell a customer that the claim cant be paid out. What are these insurance companies for we pay so much money just to be told sorry your claim is rejected. can anyone help me? Do I need to look for a new company to insure my other phones. Many people just claim and say they lost there phone and are paid out"