I cant find away to put the AT&T carrier billing back on Google play store

Hi my name is Shantelle Gibson and yesterday I had the perched blockers off my phone whenever I went to try to make a purchase on my game it wouldn't let me so I called AT&T back they said if I enabled the AT&T carrier billing the it would work but it made the AT&T carrier billing disappear and all it will show is make a purchase with a credit card redeem code and purchase Google Play points ( I even talked to a Google play store worker he told me to turn my phone off take the sims card out and then put ti back in and restart the phone twice and that should fix it so I tried it and it did not work and I've spent most of the night trying to find to get my AT&T carrier billing  back on my phone ( Samsung Galaxy Note 10 plus ) and nothing has worked to get the carrier billing back on my google play store  it won't even show up