Disrespectful Service and Denied Exchange at Lufian Store

I just bought eight things from the Forum Lufian store in Kayseri, and now I want to exchange one of them within two days. But, when I went to the store, the cashier helped the customer who came after me first. When I expressed my concern, I got a dismissive reply saying, "You'll have to wait a little while for the exchange." To make things even worse, they asked for an additional fee for the exchange, even though I just wanted to trade it for something of equal worth. Then the store manager came over, speaking in a rude and impolite manner. I think it's not okay for a company to hire rude people as managers. In the end, they didn't exchange my item, and they didn't process a refund. I'm really looking forward to getting a response about this as soon as possible.