Domino's pizza would guarantee 30 minute delivery or it was free?

Starting in 1973, Domino's Pizza had a guarantee that customers would receive their pizzas within 30 minutes of placing an order, or they would receive the pizzas free. The guarantee was reduced to $3 off in the mid 1980s.

I think their policy changed because of us at SJU. We ordered so many pizzas between 1:00 and 2:00 am that they could not keep up and were losing money.