How to hard reset a Samsung SGH A157 - Nokia 6300 Cellular Phone

What is the above steps do not work? I bought the phone in USA 3 years back while I was there as a tourist. For lat 2 years I am in India and trying to unlock the phone. AT&T is not responding to mails and I wonder why they do not want to give me the unlock code since I am not returning to USA to use their service

SGH-A157 Network unlock procedure:
Step 1: Remove sim card from phone and turn the phone on.
Step 2: Dial *2767*3855# This will initiate a Full reset for Samsung A157
Step 3: Once the phone restarts, dial #*7337# This will remove sim lock and reset phone
Step 4: Now insert your sim card. and restart the phone.