I feel your pain! I too have a teenage son (age 14) who doesn't listen to half of what I say & we both suffer the consequences of that on a regular basis. In addition, he also has ADHD, which means of the 50% he hears, only half of that stays with him for more than 3 minutes!

I do agree with the other posters that it was your son's fault & Subway had no obligation to make it right for you. HOWEVER, in the interest of customer service, I think that the manager on duty should have opted to make another 6" sandwich of the same kind as the original order & let you pay the difference (if any additional amount was due.) Having worked in retail (thankfully never in food service), that's what I would have done. It's kind of like taking a coupon after you have already completed the sale because the customer had forgotten they had one. It's not required, but it is good customer service & promotes brand or store loyalty.