[nouveaux]

I'm not sure this is a good comparison. If you cancel your AT&T account, the assumption here is that you're getting rid of your number. At that point, you are not retaining service.

Based on their website[1], you can have an account with pay as you go. There is no reason to assume that if I change to a month to month agreement, I would have to create a new account. Why shouldn't the rollover minutes stay with the account? OP paid for it already.

To go back to the AT&T analogy, if they offered a prepaid yearly contract with rollover minutes, and I lose those minutes because I switched to month to month, I would be pretty angry.

[1] https://www.snowflake.com/pricing/