at&t authorized it but l can't unlock my iPhone

i filled unlock request form and got email from at&t says

to unlockyou need to follow instruction . i have done many times those steps but it doesnt work.

here is what i got and tried many times...

We have reviewed your request and confirmed that you are eligible to have the requested iPhone unlocked.

Please allow 24 hours upon receipt of this notification to complete the unlock.

To complete the unlock, simply:

1. Open iTunes on your Mac or PC and verify that you have Internet connectivity.
2. Ensure a SIM card is inserted into your iPhone.
3. Connect your iPhone using the dock connector to USB cable that came with your iPhone.
4. Backup and restore your iPhone using iTunes. For information on backup and restore, please visit http://support.apple.com/kb/HT1414.
5. After restoring, your iPhone will be unlocked.

please somebody help.this is so frusturating!!! i have been trying to figure out 3 days. no luck 😟