I want to pay off the balance on an auto loan using a credit card. The bank accepts CC (visa,mc,discover only) but it comes across as a cash advance (found this out because it was declined, called CC and they told me cash advance limit is 1k per day).

What other option can I use to pay this off....$5,600
I have Citi AA and Amex gold reward and would prefer to use the Amex.