Self-help is the only way
The only way I have found to keep abreast of equipment change is to subscribe to the paid version of Expert Flyer to monitor the equipment change. Once a change is detected, you will receive a notification from EF and you can then re-select your seat before the automatic seat assignment.[/QUOTE]
Thank you for the EF suggestion. I switched to another flight having found it on my own. A/C was no help although they did the switch.