Try sending Bodog a cool, calmly worded email with a thorough explanation of your side of the story. Despite how I feel about them overall, their customer service was always courteous and understanding, and they don't have that "you're talking with someone from a third world country" feel that most casinos have.
A long time ago when e-check (ACH) was discontinued, I had made a deposit to Bodog about the day before the cutoff, so their processor never took the money from my bank account. I too had forgotten all about it, but a few months down the road I got the same email threatening negative action against my credit report. I replied to them and the guy that responded back was apologetic and said that it was an automated email that goes out to accounts that are in the negative.
In my case, I actually still owed the $20 or however much it was. Your situation is a bit more complicated. I'm sure if you reply to that form email and explain your situation - from the top - that they will get back in touch with you one way or the other.
This isn't the first time someone had this kind of problem with Nucharge. I'll see if I can find a link to that other thread now.
In the meantime... get started on your reply email. Type it up in Notepad or Word or Wordpad first, and when you've got it just right, copy and paste it into your mail editor.
EDIT:
Found the thread. In fact, it was one you had posted in. You used to be CowboysTX.
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When all is said and done, if they in fact do take some sort of action against your credit report, you can dispute it with the credit bureau. I'm pretty sure the credit bureau would be on your side with things of this nature. The credit report thing might even be an empty threat, for all we know.