Activation Lock for iPhone 6
I have an iPhone 6 with me right now which has been given to me by my cousin, which is also given to him by his father. This was purchased way back 2015 in Korea, but I have no clue about the specific shop they bought it. Now the problem I have facing right now, is the Activation Lock that is needed to open this. I have no any other current phones right now to use and has been hoping to use this iPhone 6 as means for communication while I saved up for a new phone.
Here's the thing, both my cousin and his father forgotten the credentials needed to unlock this. In addition to this nightmare, they have no receipts or boxes lying around as it has been long gone--since this was purchased way back in 2015, 27th of July.
I have been trying for whole day to find ways to get it open, and even contacted Apple for this inquiry but I have no other proof that this phone has been passed down to me like an heirloom, with no documentation of some sorts.
Is there any other way? Given that this device was from 2015 and all possible proof and Apple ID has been long gone and forgotten like a relic from the past. I need answers and assurance, as I need this phone for my daily use. TIA.
Earlier iPhone models