tablet locked out-apple refuses to help

i bought a tablet for my son and made him an appleid etc. long story short i thought he lost his tablet so i locked it. i found it days later and attempted to unlock it. the unlock didnt work it just continued to show a loading circle for hours while i left my phone sitting there. i then attempted to erase it thinking that would help but it did not but only made it worse. the tablet seemed to have been erased but still shows on the phone that it hasnt. when i use the email and password to log onto the now "factory reset" tablet and it will not log in saying its the wrong user or password. this isnt true as i use the same password for other things.

ive gone to the apple store where they directed me to a apple link for lock out help. i did everything they asked like providing proof of purchase from bestbuy but they responded with "we weren't able to complete your request to remove activation lock for this device" "we wont be able to review additional requests or documentation associated with this device"

honestly that sounds extremely lazy of them and really put me off from buying any apple products in the future.

does anyone know how i can fix this table?