If you’re having trouble processing a customers credit car payment, here’s a template you can use to send your customer a letter telling them that their credit card was declined.
We have received your request to order [product] with a total amount of [amount]. However, we regret to inform you that at this time we cannot process your order due to the invalidity of your credit card.
We accept other payment methods should you want to go through the order.
Thank you and have a wonderful day!