[Name, Company Name & Address here]
I am writing in to inform you that I dispute the recent invoice sent by you.
I received the invoice [no. here] on [date] for amount of $[amount]. I don’t agree with this invoice as the [state here reason for the dispute]. I am enclosing a copy of my purchase order for your reference.
I would gladly make the payment when I receive the correct invoice from you.
In order to clear your account as soon as possible, I request your prompt attention into this matter.
Encl: Purchase Order Copy