Activation Lock

Lost my phone six months ago and surprisingly someone found it and gave it back. problem is its already been reset and activation lock is showing a different apple id, its showing a gmail account was used and my previous apple id is a yahoo account... so no way of activating and using my phone. Apple support by phone is telling me to present the proof of purchase to remove the said iCloud Account, problem is phone was purchased at Dubai and sent as a gift by my niece here in the Philippines. The only proof i can tell Apple is the apple id i used with this phone and if they can match the account and the simcard number used previously which i'm still using right now. Is there any other way for me to remove the iCloud account with the said circumstances.