[NAME, COMPANY AND ADDRESS]
I believe there has been a slight mistake.
I have just received your [DOCUMENT, ex. your account summary for June]. Unfortunately, I am unable to reconcile your invoices to the $[AMOUNT] figure you state as my account balance. My records indicate as follows:
INVOICE/PAYMENT AMOUNT
[LIST INVOICES AND PAYMENTS]
I have taken the liberty of enclosing copies of the above invoices and checks. Please check your records to determine the source of the discrepancy and call me at XXX-XXXX once the difference has been reconciled.
Sincerely,
