We were told that the bassinet seat could not be reserved for our 16 month old because it was on a first come, first served basis. We arrived extra early and were the first to check in. At check in, we were told that instead of a bassinet seat we would instead receive the empty seat next to my wife and gave a printed ticket with a seat number for the baby. After my wife boarded and she and the baby took their seats, a man approached them with a ticket with the same seat number as the baby. The flight attendant forced the baby out of the seat and said they could not give a bassinet seat. My wife called and told me and I called customer service right away. The customer service representative said that we needed to reserve the bassinet seat, which is the complete opposite of what I was told months before when I actually reserved. In addition, they gave my baby a seat, only to oust her from it before the plane took off.