Seat assignments are never guaranteed. If reseated, a refund is processed automatically at flight closeout when the system realizes you were not accommodated in the seat you paid for. There is nothing in writing the agent can give you; it's an automated process. You are not entitled to any compensation.
Originally Posted by
MADPhil
On the CR9 where seat 4C is in coach it is a bulkhead seat and possibly more suitable for a wheelchair passenger.
^ Bulkhead passengers are the most likely to be bumped for disabled passengers. Not only can the airline move the original passenger, but it would be illegal
not to accommodate the disabled passenger.