How to disable pre authorized payment system?

Cancel your credit card if you don't want this but fizz the payment to do with a credit card

Unsubscribe if you don't want them to charge your card any more. This is the only option for payment.

I will not worry about that. Fizz is a brand new company, and giving us better service with really reasonable price. So, we should be patient and give them a chance to improve the service. I was charged twice ($32 x 2) for my mobile plan in 10 days. I chatted with them, and show them my credit card transaction. They immediately refund to me. So, I am not worry about that. They are honest company. As I said above, I am okay if their system need to improve - because it is a new company. I switched all my 4 mobiles and internet to Fizz. Everything is okay.

It's a prepaid service , unsubscribe ?

You can add a prepaid card and use it as default. And remove your old cc.