By changing from a higher contract duration e.g., 24-months commitment period to lower contract duration e.g., 12-months, a proration of the cancellation fee will be applicable whereby you will be charged per contract's month balance against the maximum cancellation fee agreed upon during sign up for the offer.
A proration of the cancellation fee will be applicable whereby you will be charged per contract's month balance against the maximum cancellation fee agreed upon during sign up for the offer.
You will start a new contract with 12-months commitment and receive the corresponding discount for that duration.
Check out how a cancellation fee is calculated with examples via this link: