I had that trouble with a Blaupunkt radio in a BMW, the guy I got it from gave me what he thought was the code but it didn't work. After 2 weeks of crap including faxing a copy of the title to prove ownership, they still refused to give me the code. I finally got a human in tech support (after hours on hold) who had the code but could not give it to me, I told him the code I had been given by the previous owner and he said that was not correct, but if he was me he would flip the second and third numbers, I did and it work. I don't know if I would have gotten it if I didn't have the correct numbers just not in the right order.
2000 National Tradewinds 7373