This happened to my First Tech/Addison Avenue cc:
A few months back I paid my statement balance of $334 and a few days later there was a fraudelent transaction on my account for something silly, like $4. When I called to report the fraud the payment had not gone through yet. So they cancel my card, said they would send me a new one, etc. A couple of days after that I remembered the payment and called to make sure it got applied to the new account. The rep I spoke with said "Yes, I see the payment. It's still sitting on the old account. I'll submit a request to get it moved over." Now this whole time I don't have online access to my cc account because once it was reported it disappeared from the website.
Received the card, still no online access. Called CSR, they told me to wait, still no access. Called again, they finally get it going. What I saw surprised me. I had a CREDIT in the amount of my payment. Now I was totally confused. I called CSR again. They said I made 2 payments of $334. I felt bad. I thought I should be honest. I told them I did not make a double payment. CSR submitted a request to research second payment.
Called my own bank and verified only one payment was made. For a few weeks after that I refused to use the card because I was convinced that any day they would yank out that $334. Any day...
Finally after almost two weeks of not using my card I said "Forget it!" and started shopping. And here we are today: $334 worth in free merchandise and food later I still have not heard a peep out of FTFCU about the whole thing.
I am a cc CSR, and I mentioned this story to one of my own customer's the other day and she said the same exact thing happened to her with a Macy's card! Nothing ever came of it in her situation. I told her I was worried about my the ccc one day dinging me and she said: "They won't touch you. It's $300, not $3000."
Everyone at work tells me I will be sitting on pins and needles for the next year, that they'll get me any time. But the more time that passes the more I think "Wow... did I get away with something?" 
Has anyone had anything similar happen to them? Are these common occurences?
About 15 years ago JCPenny credited my account for about $150. I called to inquire and they said they will look into it and get back to me. I guess they are still investigating because I haven't heard a peep. Oh well, I like freebies.
Does it have to be with a CC CSR? I order a lot of things from Amazon and a lot of it is on subscribe and save. We get lots of dog treats through them. I usually order a 3 month supply at a time. One order, two of the bags of treats were spoiled. I called to get them to refund it, which should have been about $8-9. They said ok, and the next day I noticed they had refunded my entire order, not only all of the dog treats but other items I ordered along with them for about $250. I called to tell them it was a mistake and that I was only asking for $9 and the CSR thanked me and said for being honest and a long-time customer that she was going to leave the $250 credit.
Starting Score: ~500 (12/01/2008)