Turkish Airlines Did Not Allow My Pet on Board

I purchased a THY ticket through the Etstur agency and called the customer representative to travel with my pet in the cabin. They told me that I couldn't make a reservation without knowing the dimensions of the pet carrier, so no action was taken. Two days before the flight, they called and said I could make a reservation. I've been calling for 3 days, and even though I mentioned I would use an astronaut carrier, they still asked about the dimensions and did not proceed with the reservation.

Two days before the flight, I called again, and this time they said there was no availability on the flight and rejected my request. Despite the inconvenience they caused, they told me I could change my flight by paying an additional fee of over ₺1000. I sent feedback but received no response.

I sent the call recordings and their timestamps so they could listen, but still no response. I feel completely deceived. They also don't provide a full refund; half of my money is deducted. If pets are not allowed on flights, they should say so to avoid such issues. I can't put my pet in the cargo hold due to its sensitivity and risk of a heart attack. We have one day left until the flight, let's see how it will turn out.