A comedy of errors! Two days after the switchover to the SABRE reservation system check-in was still delayed a lot because they never trained their staff on the new system! My SAT-MEX flight left and arrived two hours late. There was no announcement of the cause for the delay. It took the agents about 10 minutes to check a passenger. As passengers finally trickled to the gate there was no agent and no sign confirming that this was an Aeromexico departure gate - and there was no plane. On the return May 29 things were still a bit slow that's when the agent told me that she had arrived at work on May 22 to find totally new screens on which she had received no training. The system also told them (on May 29) that I hadn't paid when in fact it was a prepaid Expedia ticket. Apparently they had changed the flight number right as they were switching systems and my reservation was not transferred correctly. After my flight boarded they announced that the co-pilot hadn't arrived! Hence a half-hour delay. Totally amateurish performance throughout by this airline which I will try to avoid flying.