Invoice of the iPhone

If you purchased this iPhone from:

• The online Apple Store, you should have been provided with an email with the invoice.
• A "brick & mortar" Apple Store, you should have received either a paper receipt or that receipt was emailed to you.
• An Apple Authorized Reseller, you should have been provided a receipt.
• From some other source, you will need to contact them.

What bill? The purchase of your iPhone? Something else?