Female customer calls cops on computer shop owner over sketchy scam

I went to a computer parts shop to buy a used graphics card for 350,000 won. I pulled out seven 50,000 won bills since they sell cheap used stuff and it gets crowded. The graphics card was 310,000 won, so I thought they'd give me 40,000 won in change. I handed over the 350,000 won and asked for 40,000 won back, but the owner said he didn't have cash right now and told me to "put it on credit" ㅋㅋ What does that even mean? He said he'd deduct it from my next purchase lol. I was like, fine, just give me back the 50,000 won bill, I'll transfer you 10,000 won. But then he said he only does cash transactions for used parts, no transfers allowed ㅋ So I said, give me the 50,000 won bill then, I'll go exchange it for change. The owner got all flustered and was like, how do I know you won't just take the 50,000 won bill home? So I said, no, I'm putting the graphics card here and coming back with the change, just give me the 50,000 won bill. But he was like, whatever, just come back next time, why are you making a fuss over 40,000 won? ㅠ I said, I'm just not buying it. Give me my money back. He was like, why would I give it back ㅅㅂ Don't you know used purchases aren't refundable? Just come back next time. I said, how am I supposed to know when I'm coming back? I barely come here once a year. Fine, you already said the 40,000 won is on credit and I already bought it so no refunds, right? Then suddenly he just got in his car and drove off ㅋㅋ I was so dumbfounded I asked the staff what to do, but they said used parts sales are outside their authority. Anyway, there's CCTV everywhere so they'd have footage of him taking my money, so I immediately called 112 and the police came. But the owner and his staff weren't answering my calls and I waited over an hour and he didn't show. The police told me to just go file a complaint at the station since there's no way to get the money back anyway. So I went to the police station and just filed a complaint against that bastard. He's in his early 40s, apparently a somewhat well-known dealer in his area. And there are seriously a lot of punks in Yongsan, but for this well-running shop in Gyeonggi-do to pull this shit ㅋㅋ