How can I lodge a formal complain to AT&T so that someone in management can hear me?

I have been a customer of AT&T for quite a while now.  Recently, I have encountered an unbelievable situation with AT&T.  I am hesitant to change anything with AT&T as 9 out of 10 times, there is some charge that wasn't explained to me, etc.  So when I contacted them (as I was instructed to) when my internet promotion price ended, I was told that AT&T could reduce my inflated internet price back to promotional level, AND I could have a tablet for $.99!  I asked many questions from all angles, including "Will this change my wireless bill at all?  Will this be a separate charge to access the internet each month for the tablet?  Will this be like a line on my wireless bill?"... thinking I had covered it all.  I have it all in writing.  I was instructed no, and that the 2 year contract pertained to the internet.  Naturally I started having red flags when the emails started coming in.  They were also bundling or combining my internet and wireless accounts.  But I waited.  Finally I called when I was sure that what in fact had happened appeared to be that I had just in effect bought a $240 tablet (because sure it is .99 to purchase but now I was paying $10 a month for internet access, which I  DO NOT NEED). So in THAT conversation I was assured that it was alright.  Send back the tablet, no harm no fowl.  I do it.  I called again when my bill was incorrect.  No problem, I was told... we received the tablet, all is well, no detriment.  I pay my correct bill.  Now my bill is $169.44 too much because they charged me a termination fee.  So now I engage in my 4th call/chat to correct THAT problem.  Now almost 4 hours of my life on this issue.  It is petty, but really?  Isn't that ridiculous? At&t management read this!  I cannot believe how much trouble I have encountered for this silly thing!  Teach your people to know what they are selling.  Try harder to make it so your regular customers are not put through this hassle.  Please!