I am the Office Manager.

If I sign off on, thereby authorising, an invoice for services, leave it alone.

Do not under any circumstances question it.

I do not sign off on anything that I do not feel is correct, whether it be a $5.00 supply charge or a $15,000 renovation bill.

And?  The invoice was to fix YOUR BLOODY VOICE MAIL.

Bite me.

That is all.