unlock att prepaid device bought from market place

i purchased a prepaid att phone in box with all the creditials and its telling me when i try to unlocck this device that i have to get the account owner to remove device from their accunt , now i have no idea hiow to contact this person or even know who the owner is , i called the 800 number from the un;ock portal gave me to unlocl k this device not only did they tell me i am xcrewed but was rude and well putting it bluntly they freaking said the device cant be unlocked without the iwbner not even from a att store because it wasnt bought at att . now is this how att conducts buisness i mean i asked them if i bought it froim ebay then what he said the same thing ...i am readin the att requirements and it tells me that i bought it from ebay or similar place i caan get sa device unlock aproval even if i dont know who the owner is and i culd do this onlione whatb is the problem i need this phone unlocked so i can use what i paid for i am almost 100 nmiles to the nearest att store i live in a very rural area besides i have alresdy been tpold due the facr i didnt purchase from a att store could\nt be unlocked i am disablke and xant drivw anyway i need help with this...

can somwone please tell me how tp get the unlock devic3 code please