Dear Felix
Thank you for your recent order.
Our records indicate that, as of [DATE, ex. June 11], we have not received payment for your purchase of [LIST PRODUCT (S) PURCHASED, ex. a dining room table] on [DATE, ex. May 11]. Please consult your records to verify that we have not made a mistake. If payment has already been sent, disregard this note and accept our thanks.
Regards
Lydia