Why is AT&T so bad with customer service?

Nothing but problems since I switched over AT&T but if you need help you can't get it. I was offered a promotional gift in store but I guess it wasn't a real thing so now they are trying to get me to pay 400 dollars for the "free" gift. Which by the way was an old model smart watch they had just laying around and couldn't sell. When I noticed the extra charge I wanted to find out what the problem was but NO that would require actual customer service. I tried the chat to straighten things out but it just crashed over and over and over and over and over. So I called into their number and talked to that stupid automation thing which couldn't even get me to billing. After the tech service people transferred me over to billing I get the run around because they just disconnect you or maybe it's just my AT&T service dropping calls? AT&T is TERRIBLE I can't get an answer out of anyone and they never callback after getting disconnected when their service drops your call for no reason. does anyone else regret switch to AT&T?