I am not sure of the 'blue rewards'... but when you get the movies in the mail you can keep them for as long as you want, but once you trade them in for a movie at the blockbuster store you only get to keep them for a couple days (like if you actually just rented it from the store, there is a time limit). I don't know if the blue rewards is different, but that is what the regular blockbuster online is like.
We have had trouble with blockbuster online. They have sent us broken and scratched discs before. The last straw was that we rented a movie and it was sent to us scratched and didn't work past a certain point. We went online and filled out the form saying that it didn't work, so please send us the same movie because we still want to watch it. We received the movie for the second time in the mail and they sent us the exact same disc that we specifically told them did not work!! It made me so mad.
I went to the blockbuster store and they couldn't help me or exchange it because the store is no longer the same company as blockbuster online or some bs like that.. I went home, cancelled my subscription, and signed up for netflix.
Sorry for the long post, but we just had bad luck with blockbuster online and I finally got fed up with them and just wanted to share my experience with you. Hopefully you get things figured out.