Not sure if you still have it installed or not, but you can just load up the previous game, get the updates, and play on. No need for a new copy. Do you still have your old login and password?
As far as an issue with the eTailer, you would need to take that up with them. I am not sure what they would mean with "You Don't Qualify...." as there is no qualification, or subscription required.
I guess I'll give this copy to my girlfriend then. I have the Imperial Edition, and it was prompting me to buy a membership. I was under the impression that Tamriel Unlimited didn't require a monthly fee which is why I bought it.