Why is this $ 252 Groupon mistake my problem?

When Rebecca Yonker found a two-for-one deal on Cedar Point amusement park tickets online, she jumped at the offer. For just $36, she could get two admissions to America’s Mecca of roller-coasters. That is until she learned a Groupon mistake had been made.

Turns out, the offer was more like a one-for-one.