Product: Credit card or prepaid card

I was charged on XX/XX/XXXX to my chase XXXX XXXX XXXX for {$620.00} at XXXX XXXX in XXXX, XXXX. As soon as the charge posted to my account, I notified Chase that the amount was incorrectly charged as the bill was supposed to be for about {$100.00}. We had thrown away the receipt since the amount on it was correct and we did not think there would be any issues. I attempted to reach out to the restaurant numerous times and they responded that the charge was incorrect and they had processed a refund. Chase denied any refund had been attempted and the restaurant did not respond to any more attempts at contact. Chase told us that since we did not have a receipt, we would be unable to dispute the charge and the only way to deal with it was to mark it as fraudulent. I proceeded to file it as fraud, i was sent a new credit card, and the amount was credited to my account. I did not hear from Chase again. On XX/XX/XXXX, the charge was re-posted to my account. I called Chase as soon as I saw it on XX/XX/XXXX and questioned the charge. Their response was that the charge had been decided not to be fraudulent so they were charging me for it again. I responded that I had email copies of correspondence with the restaurant where they had admitted to the incorrect charge and that they had tried to refund me. I asked if I could send this in as proof. They said yes and that they would send me a letter so that I could send the proof in with that. I attempted to reach out to the restaurant at this time and was again ignored. After posting reviews on the restaurant 's social media page, the restaurant finally responded and stated that they had already refunded us the money which we never received and which Chase denies. On XX/XX/XXXX, I reached out to Chase to let them know I had still not received the letter. I was told it can take up to 10 business days and to let them know if I still had not received the letter after that time frame. On XX/XX/XXXX i received an email that there was a letter waiting for me in my account online which I was able to download and see that this was the letter supposed to be mailed to me on XX/XX/XXXX. On XX/XX/XXXX I sent in copies of the email correspondence to Chase with a description of what had been occurring. On XX/XX/XXXX Chase called to let me know they were denying my dispute since the window for dispute had ended on XX/XX/XXXX and because although the email showed that the restaurant admitted the incorrect charge and stated that they had refunded me the money which clearly had not happened, there was no amount stated in the emails for how much the charge should have been. In all of my phone calls with Chase, of which there were about 20 if not more, not once did anyone mention a deadline to dispute the charge or deadline to mail in proof. Even on XX/XX/XXXX when I called to complain about the re-posted charge, I was not told that there was a deadline. Today, XX/XX/XXXX, I still have not received the letter from Chase that they were supposed to send me to send in my proof. Chase refused to contact the restaurant or to have the restaurant provide a copy of the receipt to show what the correct charge was. I requested that they obtain a signed receipt from the restaurant if they refuse to credit my money and prove that the charge is correct. This charge was for over {$500.00} more than the charge should have been. Even if I had ordered every single thing on the menu at the restaurant the charge would not have been that much. Chase refuses to help me or provide any customer service on a card that costs a $ 450 yearly fee to have.