> Tried to setup auto pay and it would break. This happened a few times, so I left it broken figuring someone would call and we could sort it out then.

Never do this in the US. You need to proactively call them to resolve the situation. The standard thing for nonpayment -- which maybe Frontier didn't have working, but you're taking a real risk -- is for these to go to a collections agency, and it will go on your credit record, which affects your future ability to get credit for large loans of various kinds.