Following a solid week of complaints from users, AT&T has announced that it will be offering iPhone 3G customers who are upgrade eligible in July, August or September of this year its best upgrade pricing ($199/16GB, $299/32GB) on the iPhone 3G S beginning tomorrow, June 18. In an open letter, the company states that “[l]ike most U.S. carriers, we offer a variety of phones that we sell below our actual cost when customers agree to…