Why can't I get more than one 20 ounce w/my points? bogus...

I had points from the Coke Zero Enjoy More Madness. I had a total of 11 which doesn't get you anything really. I did submit for one 20 ounce Coke Zero as I figured with the 11 I would atleast be able to get two cokes then end up losing the remaining 3 points. But the system says I already used the amount allowed which was only one! I guess this is bogus too since you can't get anything worth while anyway unless you racked up huge amounts of points and then you only get one thing if the points don't add up. Why bother doing this stuff if your gonna end up screwing it up in the end w/too many stipulations. Damn I bought the 12 packs entered the codes entered the brackets won the points...I can't even get 2 free 20ounce sodas for that...my goodness give me a break!!!!