Subway's "Fiery Footlong Frenzy" contest is nothing but a rip-off.
Within two weeks, all my local Subways had no more 32 oz cups with contest codes.
The codes on Sun Chips Monterey Jack and Tomato are repeats - there seem two be only three or four different ones printed on the bags, and Subway's website tells me "You've already used this one. Sorry."
The stickers put onto breakfast sandwiches are also extremely limited in number. I got the same code on two different stickers IN THE SAME VISIT! And (as noted above) they don't allow use of any code entered before.
Consider this: With over 140 trillion possible combinations of 10-letter codes, why should there be any repeats?
Obviously, to lure people into buying their products to enter a contest in which the customers cannot possibly win a prize because the contest codes are no good.
Subway gets your money -- you get frustration.