One assist - insurance rejeted

I had purchased my iphone * plus and insured with one assist. My insurance amount was Rs ****.
When I went to Goa I lost my phone while I was withdrawing money I left my phone in the atm counter and few minutes later when I came to get my phone it was not there. I was in an hurry to rush out of atm as my friend was not keeping well. I came to withdraw money to take her to hospital. In the hdfc cctv footage it is clearly captured that one person is taking my phone . This details has been shared to me by the Anjuna Police. I raised a complaint immediately and raised insurance claim. Gave all the details to OneAssist as per the demand. In my distress , in the description form of the insurance claim I mentioned as below ..

"I went to withdar money from hdfc Anjuna Branch atm. While withdrawing money I had kelp the phone
in the atm counter and while leaving the atmI forgot to take my phone. Few minutes later I went to
atm to check my phone and realized that the phone is lost. There was no securiy guard at the atm."

After * weeks of waiting period , One Assist closed my case telling

the subject claim is not admissible under section ** act - Loss or damage caused by wilful negligence (No proper care of handset has been taken by insured to safeguard the property)

Willful negligence is a very bad term to close my case. I bought a phone spending around **, *** rs an I will willfully loose it . This itself is really absurd. Based on a single line of my description my case cannot be closed this way. They should have looked into the further called me for details understood what happened and then they can take decision.

This was clear accident and for accident only we take insurance. In such cases One Assist should have clearly mentioned to me these clause while taking insurance which has not happened. They should have educated me telling that unless a third person snatch a phone from our hand or snatch our hand bag which has phone , rest all cases are willful negligence and insurance will be denied for such cases .

Please help me to ensure that OneAssist opens up this case , look into the details and take a fair decision rather than just closing a case based one on line description.