Turkish Airlines Charges Extra Fees Without Informing

On 04.08.2023, I purchased a ticket for my 9-year-old cousin for the Istanbul-Baku flight on 11.08.2023 via phone from Turkish Airlines. Initially, the ticket was ₺4,100 on mobile, but they charged ₺5,300 because it was for a child passenger. Despite the payment being processed, I was asked to present my card at THY agencies and sales offices because the transaction was classified as 'Risky'. I was on vacation in a small town and was told at the local agency that only sales offices could handle this process. The nearest sales office was 100 km away. The call center informed me that the sales office closed at 18:00. I set out and arrived at the office by 17:00, only to find it closed. Their phones were unreachable due to a switchboard malfunction. I had to return the 100 km back. Early this morning, I went back to complete the process. Despite no prior information, I was charged ₺2,200 for baggage and ₺1,600 for 'Child Transport' during the ticketing process. After handing over the child to the staff, the mother left the airport, and the child was not allowed to board and was brought back without any explanation. A significant amount of money and time was wasted. The question is, how ethical is it to charge a 'Child Transport' fee without any prior information, especially when the ticket was already more expensive for a child passenger? Additionally, why don't call center agents provide the necessary information? Lastly, isn't the lack of coordination between the THY call center and ticket sales offices either very amateurish or very unprofessional?