How do I file a complaint against an AT&T store employee

I went into an AT&T store to try and get my data plan upgraded to unlimited. I have my phone and my wife's phone that needed to be upgraded but my son's phone is a simple flip phone that is intended for emergency calls only and didn't need to be upgraded at the time. I would eventually need to upgrade his phone, when he gets a little older, to a smart phone with data and have a simple plan for my daughter when she gets of age to have a phone, but that would be 3 years down the line. The employee said that I was on an outdated plan and that I could keep and add a third line with data and would be cheaper than the plan I was currently on, if I upgraded to the Unlimited Elite plan with three lines. He ended up wiping out the old plan and putting four lines on Unlimited Elite. I went back to the store yesterday to try and get this resolved. He then proceeded to drop one of the lines to Unlimited Standard but said that he could no longer get the original outdated plan back. I pointed out that I was then paying for a fourth line that wasn't needed and that the only reason we added the fourth line was to keep the original plan intact. He said that he couldn't eliminate the fourth plan and that I would need to call AT&T customer service in order to get it removed.

I just spent and hour and a half on the phone with two different people. FORTUNATELY, the woman I spoke to last was able to put my phone and my wife's phone on the Elite plan, drop my son's phone to the Standard plan and remove the fourth unnecessary line that was added...WHICH IS ALL I WANTED IN THE FIRST PLACE!!! How much commission was he trying to get by adding a fourth unnecessary line to my plan? A fairly simple request turned into a useless additional trip back to the store and an hour and a half phone call to try and fix the mess he created. As a customer support representative, he is suppose to be trying to get issues resolved and the best plan that fits the needs of his customers, not what plan will get him the best commission!!!! It is absolutely absurd that I had to jump through that many hoops to get this done.

I would like to file a formal complaint against this employee. If he isn't working for the customers, in the end, he isn't helping your company keep those customers, in essence working against the company's best interests.