Issue with Turkish Airlines Miami-Istanbul Flight Booking

I purchased tickets from Turkish Airlines (supposedly a Star Alliance member) on October 21 for the 11:20 AM Miami-Istanbul flight a week in advance. We received an email with our ticket numbers. Since we were traveling with a baby, we bought seats with extra legroom and a bassinet. On October 20, after finalizing our newborn's passport details, we called Turkish Airlines customer service to add the baby's information to our tickets and made the additional payment. This is where the problems began. On the morning of October 21 at the airport, we were informed that our tickets had been canceled. After two hours of repetitive conversations with customer service, no tangible solution was offered. We were told that the headquarters would get back to us, but no one did. It felt like the issue was our fault, and we were left to deal with it on our own. When we mentioned that we had not purchased refundable tickets, they offered a laughable solution of adding a refundable feature for ₺60,000. Ultimately, we had to buy new seats ourselves. We were financially and emotionally distressed and felt let down by a company that prides itself on being one of Turkey's best and a global brand.