Payment not accepted because it's below minimum amount

I have been trying to pay the balance of my bill for 2 days and am not able to make payment over the phone or online.  I initially intended to split the payment between 2 cards.  Payment of over $200 went through with no issue.  I'm trying to pay the remaining portion of $8.81 but payment keeps getting declined on two cards.  I contacted customer service both days and was initially informed that it may be a tech issue and to wait until today.  Today, declined again; agent sent payment link through email - declined and connected to pay by phone; declined due to payment being below minimum payment.