Cancelling a payment from my account as I paid for my dad using his name

My problem is my dad needed a new phone very basic of course he is 94 years old. I took out another lebara card with his name but money coming from my account. I found out that he hasn’t been using it so I was going to cancel his sim and payment . I don’t have his number…he doesn’t know his number his memory has gone so how do I cancel this anyone know? Is there a phone number/email or live chat didn’t think this would be so difficult

Hi christobell1

A quick way to retrieve a phone number can be to call your phone from his device?
You don't need to answer, but you'd then be able to see the number (if phoning a landline, use 1471).

Hope this helps.

Just turn off auto renewal in lebara app under manage.