Unless the reports are due to expire on your score within the next year, I absolutely think you should keep trying!
But don't just send letters, call, speak to people. If they can't help you, ask which department can and if they can give you the number. Go higher on the chain of command.
Just a warning though, I have had very little luck getting Capital One to work with me on ANYTHING. I have had the card for 12 years, never asked for a CLI and they are digging their heels in. I'm very disappointed in them over it. In the 12 years I may have been late on 4 payments total, and currently have a zero balance so there is no reason not to extend some customer service to me. That being said, you may luck out and get just the right person on the phone.
