Need to cancel autopay but Paygonline just load load or work

I’ve moved back abroad and didn’t cancel my AT&T autopay before I left, I’ve tried multiple times to try access it and cancel the autopay (as I know the account will close it self down after a certain time of me not using it). The website just won’t work for me at all and I can’t access my account whatsoever so how will I cancel my autopay so I don’t have to keep paying these bills every few months