Dont bother to book your seats you will probably lose them

In January 2015 we booked our holiday to Cuba and were the first to enter our seats on the seating plan. Due to an huge mess in the airline computing system in November these were lost. We had no notice of this fact and did not find out until Saturday 19th March 2016. We immediately went to our local Thomas Cook Branch where the agent phoned the airline and was abruptly hung up on. She tried to book further seats which also disappeared. The manager of this branch tried to resolve this all week and hit a brick wall. In desperation I phoned customer services on Friday 25th March and was told that this was no big deal, laughed at and finally hung up on when I asked for a supervisor. We book our holidays early because although I like holidays, I dislike flying, suffer from stress and it is important that I get the seat I need. They do not want to hear this and just say that we must accept the dregs of seats that THEY have now allocated us on a "Choose your seat holidays package". Not good enough Thomas Cook. We have two holidays a year with you and are now considering cancelling our second and never booking with you again.