Cancelled tariff, still getting charged.

[NicMc]

I have phoned o2 on 2 occasions now to cancel my daughters tariff. She is living in Australia now and no longer uses the sim card as she now has an Australian sim. The account is in my name. Both times on the phone I have been told it would be cancelled but I am still getting charged 5 months after my first call to them. Is there another way I can get through to them other than the phone where I will be listened to properly and they can understand my request. They are taking money from me for something that is not being used. Its very annoying. Any help with this situation will be appreciated. Thanks.

[MI5 · Accepted solution]

@NicMc 

Guide here (use the old method) Guide: Cancelling Your Contract 

Guide: How to find help & contact O2