As always:I have just been through a maze with Vodafone. I firstly phoned the number they advertised as being to do with PoA. I had obtained a code which they took down and accepted. But then I was told that dementia is not a "critical illness" and therefore they would not cancel his contract, it would automatically expire if the phone wasn't used for three months. I argued, to no avail. Next I tried the on line chat who couldn't do anything about it but gave me another phone number to the critical illness team. That person was shocked at what I had been told and said that the contract would be cancelled and that I could stop the direct debit, which I did.
Then I got an email from the critical illness team saying that they could not trace the contract and it must be an anonymous pay as you go. I phoned the previous number again and this time the whole mess was sorted out. They had got the number wrong, and I know I didn't tell them wrong because this was our only mobile phone for 20 years and I can just rattle it off. The person I spoke to warned me that I might get a letter from a debt collection agency because this happened automatically when a direct debit was stopped, but to ignore it. I find this shocking - do they not even try to find out why the DD was cancelled first? It could have been a mistake/inability to pay/anything. My own phone is on a Vodafone contract but I will be switching as soon as it ends.
If you want to argue better
Always stop to write a letter