Regarding My Cellphone what i sold through OLX

Hi I am Anand Mohan. Actually 3 month before i sold my Cellphone(Samsung Galaxy S3) through OLX. The cell phone was under warrenty and even Insurance was there. Now after 3 months that person who bought my phone came to me and saying that he lost that phone and want to claim the insurance. But he is saying he can't claim because the bill is on my name so i will have to claim..he has done police complain but he is saying me to fill the claim form with my signature and some id proof. I want a legal advice that what should i do...Because From last 3 months i was not using that phone even i don't know that person..i don't know which sim he used in that device and how he used that phone...suppose if i will claim and after that if any problem will come because of that phone police can tell me that you claimed in month of November so you were using that phone. But Actually i was not using that phone. Even please let me know that if i am selling any electronics item on olx or any way...should i take any proof that i am going to sell my device....?? Please help me regarding that. Thanks & Regards Anand Mohan