Newbie here, apologies in advance if this isn't the right way to do this! I've never booked an award ticket before on any airline, and will be using my Citi thank you points transferred to TK to book this one.

I'm trying to fly IAD-IST 4/26-5/6. After looking exhaustively online and finding only biz class awards at 104,000 each way, I called the miles and smiles number. There is a limited space seat available for the outbound flight for 45k, but not on the return date or any dates near it. If I book economy for the return (for 30k), is there a chance that a 45k business seat will open up? (I've also read to call and get a different agent who may have different information.)

If a saver seat does open up, am I right in reading that there would only be a $25 charge to change the ticket from economy to business, plus the additional 15k miles?

TIA for any advice/tips!!