Unfortunately, the only people allowed to work on phones at the USCC store are the techs themselves. In order to get a tech, however, you have to go to a USCC store that has a tech center. If they don't have one, then going there is just a waste of gas.
As I mentioned before, the best route to take at this point is to call in to USCC (Dial 611 on your cell phone if you can, otherwise you can look up their number at their website) and explain the issue. Mention that you have taking all procedures (just to get them to shut up about it) in attempt to correct the issue, but to no avail.
After some chatting about your phone, the USCC representative should transfer you to a tech and then some more talking will go on. Lastly, they will tell you you're eligable for the replacement program and they will ship out your new phone (they'll tell you to keep the battery and back cover of your old phone). This usually takes 1-2 days and it comes via UPS.
Best of luck!