I'm currently I'm the same boat here. Purchased economy on Etihad from SIN - LIS, and my AUH - LIS - AUH routes have been changed to HiFly. Customer service is refusing to budge and denying that this is a downgrade, they just can't seem to understand the fact that a HiFly aircraft and crew is materially different and a significant downgrade from an Etihad aircraft and crew. First time flying Etihad, probably the last. I'd be happy to join in on a formal complaint with any relevant authorities.