Finally, as you go through the process on the phone a few thoughts. I'm assuming that you've already booked a seat in business class, if you haven't then what I'm about to tell you won't apply. First, be sure to verify with the agent before they start, the price you had already paid for the BC seat. The computer will want to automatically reprice the seat to the current price level. The agent must override that and you'll want to verify that the price is still the same when they're done. Second, the agent will have to credit your credit card back giving you a refund to process the coupon. When you go to pick up the tickets, that agent will want your credit card again and will recharge you at that time for the BC seat, then process the coupon to get you the first class ticket.
Finally, make sure that the agent extends the hold time on the reservation for 2 days. Some forget to do this, and the computer defaults to 1 day. So your reservation would cancel on Monday, the day before you get to the station to pick up your tickets. Personally, I like to ask the agent when they're done to send me a new email confirmation, a trick that I just learned in fact. That new email both confirms that they got the price right and that they extended the hold date for me.
If you find upon getting that email that they didn't get the price right, there is nothing you can do about that by phone. When you go to the station, bring along your original confirmation and have the agent fix it then. They need proof and the phone agent's can't see what the old price was, once it gets changed. If you find that the agent didn't extend the hold date until Tuesday, that you can call back and have fixed and of course you want to do so ASAP.
