To OP. Have you been able to resolve this? Your purchase date appears to be right at the border when the policy changed (8/27/18). If you purchased the tickets before this date you are entitled to cancel the mint flight without penalties provided the tickets was above $950 if it's a non-stop flight. If so, you should then able then be able to get your money back. You can do this without being Mosaic.
Refer to the Flight Terms and Conditions page on jetblue website under "Fares booked before 8/27/2018", last sentence (section C).
Sadly, i didn't realize the policy had changed, at least it wasn't mentioned in any other forum. I was able to use this policy back in 8/29 without even knowing it was going away
