[Your Name]

[Street Address]

[City, ST ZIP Code]

[Date]

[Recipient Name]

[Title]

[Company Name]

[Street Address]

[City, ST ZIP Code]

Dear [Recipient Name]:

When you placed your order, reference number [P.O. Number], we agreed on the price of $[amount]. However, when we charged you on the invoice dated [click to select date], we mistakenly undercharged you by $[amount]. Enclosed is the adjusted invoice. Please remit a check for that amount by [click to select date] and accept our apologies for any inconvenience.

Sincerely,

[Your Name]

[Title]

Enclosure