As a person who has had numerous issues with 5 different iPhone 4s, here is my suggestion.
Above all, Be Polite.
- Stop dealing with the Genius Bar and call Apple Care Tech Support.
- Tell the person your story with details and specificity. Be succinct, avoiding unrelated details.
- Get to a Second Tier person.
- Tell him/her your story with specificity and detail, including NOT RESTORING FROM BACKUP because if it still happens after you restore and create a new phone, it's usually hardware related.
- Tell him that you are tired of refurbished iphones and getting other people's problems.
You will get a new phone.
Be prepared to give your credit card number to secure the transfer and return the iPhone to them promptly to avoid charges on your credit card.
I had different problems with different iPhones. 3G Data, Prox Sensor, Camera, and really bad signal issues, to name a few. It happened. My current iPhone is working as designed.
The key to getting someone to work with you is to be polite, be detailed, and be persistant. It
will pay off.