I couldn't apply the Amex discount.I paid the amount requested since tax deadline is a day away. Is there anyway I could get a refund for the Amex discount?

As it turns out, we're unable to provide refunds for unapplied discounts or promotions. To ensure discounts or promotions apply in the future, please review the article below. 

https://ttlc.intuit.com/replies/7203171