No experience with redepositing miles for fee due to aircraft switch, but did have an experience where AA pulled a 767 to OGG and switched it to a B738 a few years ago. We had paid for F, and they gave each of us a voucher for three hundred for the AC switch after I explained that I specifically paid for F to be on the wide body 763 out to the Islands. Hope it works out for you.

Safe Travels