AT&T charges me a different amount every month as it is. I can’t figure out why, the bill is too stupid complicated, but the amount varies between 10-20 month t

AT&T charges me a different amount every month as it is. I can’t figure out why, the bill is too stupid complicated, but the amount varies between 10-20 month to month. Why would I ever trust those people to ACH my account an undefined amount each month? If the bill amount was actually fixed and predictable, sure. But that’ll never be the case. I really hope banks charge the carriers for bounced checks. That’s not something a consumer should have to do if their account is $3 too low because they funded the account for whatever the bill was last month.