Account terminated, overdue payment, cannot log in to pay, live chat link broken

[noootwo]

So we terminated our O2 account on 1 August 2019 since we moved abroad. Since then, we're getting payment reminders asking to log in and pay. We cannot log in as logging in requires an SMS code, which we cannot get (remember, O2 account terminated). O2 also sent us a "live chat" link which is broken:

This site can’t be reached

link.liveperson.net’s server IP address could not be found.
DNS_PROBE_FINISHED_NXDOMAIN

Any ideas what to do next? Don't feel like calling them again and waiting an hour to talk to someone who then does nothing just to be allowed to pay an outstanding balance.. Did that live chat thing ever work for anyone?

[MI5 · Accepted solution]

@noootwo 

All contact details here Guide: How to find help & contact O2 

We always recommend calling rather than chat anyway and if you call early morning UK time there is not usually any significant waiting time.

[MI5]

Freephone from abroad +44800 032 1402

[Bambino]

@noootwo  If you have moved abroad, you may not have a UK based account any longer, which will prevent you paying. You may have to speak to customer service, then get a friend or relative who is still in the UK to pay what you owe and then reimburse them.