Turkish Airlines Primefly Flight Change Fee Issue

On January 12th, I had a flight to Istanbul that I wanted to change. I had a Primefly ticket that shouldn't require a change fee. I also contacted the Romanian call center, and they confirmed that the rules hadn't changed and the change should be free. However, when I tried to pay with my card, the payment didn't go through, so I called the call center. They assisted me but charged a service fee. Later, I called the Romanian call center again, and they explained every charge to me. The person who spoke to me in Turkish and helped with the change didn't explain what I was paying for and why. I was penalized because I paid a fee during my first transaction and had to pay again. If they take my money and I can't change the flight for free as mentioned, what are the benefits of Primefly? Additionally, service fees are not mentioned anywhere. Flight change fees are not listed anywhere. Not on the website, nowhere. It's not normal for passenger information to be incomplete, and I want my expenses covered. There is no reason to pay. Even if it's the New Year, it was confirmed by the Romanian call center that I shouldn't pay for a flight change. When I bought the ticket, it was clear that the return was in the New Year, so if it was about fees, it should have been special. Also, I bought another ticket with the same card, and it worked. So it was an issue on your end, and I was penalized because, yes, call center services were not communicated to me, and I repeat, I shouldn't have paid for the flight change. I got confirmation from Turkish Airlines. And I don't understand, I bought a plane ticket to be able to make changes, now I've changed it for more than a regular ticket and paid taxes again. So if I'm going to pay more, what's the benefit of buying Primefly?