Terrible Customer Support and Service

What is the process of making an official consumer complaint for a 10+ year customer of AT&T?

I have had NOTHING but the WORST service over the last two weeks regarding internet set-up. NO ONE absolutely no one has been of any help. I spent over 3 hours, over the span of three calls, to get absolutely nowhere.  A few of the following is what I have been told:

I was not an existing customer;

then my account was suspended,

that I canceled my service

my passcode was incorrect (only to read me all of my information) and,

read me the information on someone else's account.

I understand that the 130 billion dollar company wishes to set up call centers across the world to save a few coins, but MY GOD why is getting any service, not good or great service, so (Edited per community guidelines) hard. ANY SERVICE would be greatly appreciated by ALL of your customers. 

YOU ABSOLUTELY CAN DO BETTER!!!