Turkish Airlines Baggage Fee Issue for Separate Flights

I purchased a ticket from Turkish Airlines' mobile site using my miles and paid an additional ₺480 for a flight from Izmir to Elazig with a layover at Istanbul Sabiha Gokcen. When I arrived at Izmir airport and checked in, they informed me that my luggage was overweight. I mentioned that I am a Gendarmerie personnel and that there was a campaign for us, but they said it didn't apply to tickets bought with miles. I ended up paying ₺495. Upon reviewing my account transactions, I noticed that ₺495 was charged twice, which I reported and got refunded. If I hadn't noticed, no one would have cared. My second issue is that my layover flight at Sabiha Gokcen was actually at Istanbul Airport, and they told me I would have to pay another baggage fee there. I called customer service, and a lady named S**** said they would refund the ₺495 and asked me to purchase baggage again and inform them that I wanted to use the baggage for my flight from the other airport. I did this, but they told me that since I bought it for Sabiha Gokcen, I would have to pay again for the flight from Istanbul Airport. On top of my exhaustion, I had to go through security multiple times. I want this issue resolved immediately.