After many years with Vodafone with mobile and broadband accounts I left in frustration due to repeated billing stuff ups and miscommunication. I don't want to re-hash that.

I still get mobile account bills of $0 sent irregularly and have sent emails to support asking this to stop. No answer. I've tried contacting Vodafone's call centre but I need to verify my account details (with details that are long faded from memory, e.g. old cancelled credit card for billing amounts, forgotten PIN). Are there any ways around this? I just want to stop getting reminded of how crap the billing system was/is.