Although it doesn't solve your immediate issue, you may want to consider just setting a reminder alert with your phone's calendar so that you manually purchase your package renewal each month.
They've had this issue for years with the GoPhone package renewals and it sounds like they are no closer to resolving it now than they were when I had the same issue several years ago. Rather than endure the headache of trying to rectify it each month, I would just take a preventative approach. It's too bad that still seems to be the only way to avoid it after all this time. 
(When it happened to me several years ago, customer service was willing to give me a one-time credit only; and their "solution" was for me to call each month on the day before the auto-renewal was to happen to have them check that the switch hadn't been flipped off in the "background". lol. Needless to say that's when I realized a manual renewal - dependant only on me - was truly the most time efficient way to go.)