Originally Posted by
GoAmtrak
Last weekend I made a booking for myself (eTicket) and subsequently found out that a friend could join me and that I could burn a companion coupon. The phone agent was very helpful; she simply refunded the credit card charge, but added my friend to the same reservation, preserving the PNR, and plugged in the promo code. I went to the ticket counter to turn in the coupon and run the CC charge again, and the eTicket was reissued with no problem. ^
Yes, that works if they refund the entire charge first -- but had the prevailing price changed for your paid seat since the time you booked? The system does not automatically protect the prior fare, instead giving you whatever today's price is.