Etihad Airways — Flight cancelation

I booked 4 return tikets on Etihad airlines for August 13th from Thiruvanathapuram to Chicago. My booking number was FNBYBK and confirmed tiket with seat numbers. The seats were alloted on flights numbers EY273 (TRV-AUH) and EY151 (AUH-ORD). On August 5th Etihad informed that the flight EY273 has been cancelled. The same day UAE uplifted the travel ban from India. We contacted Etihad airlines and they said we will get priority whenever the flight resume. From August 10th the flight number EY273 resumed from Thiruvanathapuram. I contacted Etihad airlines and they said no seats avaliable till Septemer. Due to our employment and college studies we couldn't wait till September, so we booked another tiket through Air India which incured additional exp of $7, 500 due to the un ethical behavior of Etihad airways.