Deeply disappointed

I bought an iPhone SE with IMEI no. *** at Tembisa store, the phone came with an icloud account of Fortunate I reset it and it went on activation lock. For it to unlock the first owner must remove it from his icloud account, another option is for the store to give me or send proof of ownership of the first owner to Apple do that they can unlock it. Please help traxe the first owner so that s/he can unlock the phone so i can use it, i tried contacting the store through WhatsApp and calls they are not helpful