They called even though the payment wasn't due. Remember collectors have consumer protection laws they have to obey.Tell the rep they don't have permission to call you and they must stop. Once they see you are aware of your rights they will leave you alone. As for credit one itself absolutely pay off and cut that card.
Credit One Bank. They call constantly if your payment is one day late or one dollar short. Crazy...even if you spoke with a rep and they supposedly noted it in your record.