do as they please

Airlink seems to do as they like. I booked specific seats due to my wife's condition and fear of flying. Yesterday i looked at the booking as we flying shortly only to find out the seats we had booked were not correct. I called them only to be told the aircraft changed from a Embraer 190 to 195. they have the same seating configuration. we were booked on 3 A-C now get shoved to 20 A-C. Then i am told that they can do if they feel like it.