Activation Lock - Previous Owner can't help
So just recently I ran into a pretty major conundrum with my newly bought iPhone 7 that I bought used. I had done my research beforehand, and the previous owner had deleted the device from his Find My iPhone and iCloud as well. Around a week ago, I updated the phone, and got hit with the activation lock. Talked to the previous owner, and the account that it says on the screen isn't linked to his. I checked the IMEI, dosen't show as stolen, and a found out that the person whom I had bought it from also bought it used. Chances are, the Apple ID is linked to a third individual I don't even know about, and have no contact with
What's the solution to this issue? I really need to use my phone, as i'm stuck with an iPhone 5S, which is quite slow and glitchy. I do have proof of purchase with all required details that prove i'm the owner of this device, so can I go to the Apple Store and get the lock removed?
Thanks
iPhone 7, iOS 13