Changing Reward Flight Query

We'd booked two Upper reward flights to Tokyo for a total of 200,000 miles, departing on 11th April. We've decided to cancel as we don't think we'd enjoy Japan as much as we'd like at the moment.
Presently, VS is allowing full refunds for flights up to 10th April, so being a day later we would lose 50,000 miles for a cancellation.
I wanted to change our flights and go to New york, but in economy upgraded to PE with our Amex vouchers. The Premier Team member I spoke to (and confirmed by his supervisor) said that you can't downgrade. The Terms and conditions seem to allow for a change to date, route and class change for a £25 fee, but don't mention the direction of change of class ( I guess most people would want to upgrade). However we want to save as many miles as possible to rebook to Tokyo next year.
I'm hoping that they will extend the refund period beyond 10th April, but can't leave it much longer. If I leave cancellation until within 7 days I risk losing all the miles!
Any advice would be welcomed!
Presently, VS is allowing full refunds for flights up to 10th April, so being a day later we would lose 50,000 miles for a cancellation.
I wanted to change our flights and go to New york, but in economy upgraded to PE with our Amex vouchers. The Premier Team member I spoke to (and confirmed by his supervisor) said that you can't downgrade. The Terms and conditions seem to allow for a change to date, route and class change for a £25 fee, but don't mention the direction of change of class ( I guess most people would want to upgrade). However we want to save as many miles as possible to rebook to Tokyo next year.
I'm hoping that they will extend the refund period beyond 10th April, but can't leave it much longer. If I leave cancellation until within 7 days I risk losing all the miles!
Any advice would be welcomed!