Dear Felix
Thank you for your order of [DATE, ex. June 10] for [LIST PRODUCT (S), ex. two Power Account software packages].
Unfortunately, we are unable to process your order because the transaction on your credit card was declined. [LIST OTHER ACCEPTED FORMS OF PAYMENT, ex. In addition to credit cards, we do accept cash, checks or money orders.] Please contact me at XXX-XX-XX to arrange for payment, and I will process your order immediately.
Regards
Lydia