SunExpress Airlines' Unfair Luggage Fees

On September 5, 2023, I checked in for SunExpress flight XQ980 from Izmir to Vienna. My luggage was weighed, and I received my boarding pass without any issues. However, upon reaching the boarding gate, my name and a few other passengers' names were announced, instructing us to approach a SunExpress boarding staff member. Around 4-5 names were called, but only one other passenger and I went to the boarding desk. At the boarding gate, our luggage was re-weighed using a mobile scale, and we were asked to pay an additional baggage fee of 80 Euros each. I contested the amount, as the SunExpress website stated a fee of 10 Euros for each extra kilogram. My ticket allowed 4 kg of baggage, while my suitcase weighed 5.8 kg. The other passenger's bag was 8 kg. Nonetheless, we were both charged the same 80 Euro fee. We paid the fee but received no receipt or documentation in return. Additionally, the other passengers whose names were announced never showed up, and no fees were collected from them. This experience left me feeling unfairly treated and frustrated. I attempted to get answers from SunExpress customer service but received no satisfactory response. Here are my questions:

Why weren't the excess baggage fees collected when our luggage was initially weighed at the check-in counter?
If the fee for excess baggage is 10 Euros per kilogram, why were we charged 80 Euros each?
Why were we not allowed to remove excess items from our luggage when we requested to do so, with the claim that airport cameras were recording?
Why were no fees collected from the passengers whose names were announced but did not appear?
Why were we not provided with any documentation or receipt for the 80 Euros we paid?

I have filed a complaint with the Revenue Administration Presidency regarding SunExpress's failure to provide a receipt for the 80 Euros they collected. I will also submit a complaint to the District Arbitration Committee in my area. I hope that this attitude, which takes advantage of passengers, receives the appropriate response, and that I can recover the unjustly collected amount.