This is CAPITAL ONE AUTO FINANCE in Dallas, Texas. They start calling the first day into your 15 day "grace period" on your auto loan and if you don't answer, their computer redials every 50 minutes from 8 am to 9 pm local time until you answer. Even when you make arrangments to pay before your 15 day "grace period" expires, they will continue to call daily until they receive your payment.
No such thing as a grace period. Past due is past due, additional daily interest accumulates when an account is past the due date. The grace period is only in regards to late charges.