This keeps coming up, perhaps the wiki needs an update so this question doesn’t come up repeatedly. Canceling a refundable fare at any time up to departure (and perhaps even beyond) is going to give you your funds back to the original form of payment which in your case is the ETC expiring March 2025. Read my post above yours as well as many different posts up thread to see what to book to convert your ETC to an FFC valid for 1 year from booking date.