Why is the Direct TV/AT&T partnership total garbage? And the website is a pile of junk. Are you one company or two?

I used to have phone, internet & Direct TV through ATT. I got rid of the bundle and kept direct TV. But none of my old AT&T logins work anymore. All of the links for Direct TV just take you straight back to AT&T's website (which is also pathetic, particularly for a tech company). I cannot access my Direct TV bill, I cannot link the accounts, all I can do is be on hold endlessly and finally get somebody on the line who also cannot help me. However, they can email me my now past due Direct TV bill but all the links to pay it take me to AT&T's website. Where I cannot pay my bill.