1. 12" Sub /= 2x 6" Subs. Order two seperate six inch subs and use said coupon. This prevents you from looking like an @sshat after your 12" sub has been rung up as such.

2. "Coupon not valid with any other offers" means that you can't use it on the same purchase with another coupon. Confirm BEFOREHAND that you want to make two seperate purchases to ensure that things go smoothly instead of f*cking everything up at the end.

Sorry bro, but it really seems like you made the transaction more complicated than it needed to be. Next time read the coupons, follow them LITERALLY (don't expect them to figure out your little plan), and help things go smoothly.