Wow only 17 days until my last day

I can't believe how fast time has gone. I have just over two weeks left at work. Today was an insane day, I had a customer who I delt with for over 45 minutes. He bought a car batter on friday and brought his old batter in at the same time therefore getting a casting credit of $10. Well the battery was the wrong one so he brings it back today, to get the right one. So far no issue. I give him the return for what he originally paid which is the full price of the battery minus the casting credit. He brings the proper batter to my cash thi battery is a fair amount more then the wrong one. So I put in his credit for the wrong batter and his total comes to basically $50. He then procedees to argue with me for 45 minutes, that I am over charging him by $10 (which is what the casting credit is) now on the new battery he dose not get the bcasting credit because he did not bring back an old battery today. I called my manger he tried exlaping it to the guy, the cash office manager tried explaining it to him. The new batter minus what he paid for the wrong battery equals the $50. There was no getting threw to this man, I was ready to pull my hair out. So now he wants my store's dealer to call him tomorrow becuase he still feels that he was over charged by $10. I wish I was a fly on the wall for that conversation.
I had another customer bop me on the head today with a roll of landscaping fabric, it just wasn't my day.
Here is hoping that tomorrow is better.