<human>: Condense the text into a few key points

I was at Subway a while back, and while I was thinking of what to get, the guy ahead of us was paying. There was some sort of deal of buying one type of sub, get another free. He had a coupon too, but the clerk denied the coupon because there was an ambiguity with whether or not the coupon was allowed with other deals. At this time, the subs were already made, he was paying, but not for both. The customer decided to only pay for one, and asked for the other free since it was made and the clerk had to throw it away. The clerk denied it. This argument went on for a while and ended up in the clerk just eating the sub in front of the customer.
<bot>: Subway clerk ate the sub, that was made but not payed for, in front of the customer after a long argument about it.