I had the same experience as Firehawk11 when I tried to watch Tom Brands' press conference this afternoon. After sending an email, I got a reply saying the code was no longer valid, and I would have to re-subscribe (and pay full price, of course). Now, I have no problem with a company limiting the number of times a coupon can be redeemed -- it should be stated clearly up front, but even if it isn't, that's a legitimate business practice. What I object to is the invalidation of a subscription that they allowed me to sign up for successfully. As I pointed out to the BTN in my email, a store that runs out of an item that was on sale does not call up everyone who bought that item and demand that they return it to the store.
What they don't know, of course, is that I intended to continue my paid subscription at least through the wrestling season. Now, I intend to never give another penny to BTN, either directly or through a cable company. I doubt they care, because not enough people will do the same to really make an impact, but it makes me feel better.