Pegasus Airlines Overpriced Luggage Fees and Unresolved Issue

I tried to add 12 kg of checked baggage for my Antalya to Basel flight, and the cost was initially quoted as ₺870 for a round trip. However, when I reached the payment screen, the price jumped to ₺6,000. I called Pegasus customer service multiple times, and they acknowledged that the price increase was abnormal but said they couldn’t resolve the issue and advised me to file a complaint. I submitted two requests, but neither resolved the problem.

Customer service admitted there was a system error but provided no assistance. With my flight tomorrow, I’m forced to travel without baggage because I can't afford ₺6,000 for 12 kg of luggage. I'm frustrated by the wasted time on the phone, my efforts, and ultimately, not getting any results.