They downloaded the phone app and registered, before placing a small order for $5 that would allow them to purchase the extra meal.
They thought they had the hang of it when a $0.00 balance showed at the bottom of the purchase order. But after then accepting the order, the full amount of the order was debited from their bank account.
They also took issue with a side order of Kiwi Crunch, which they said clearly stated it came with sauce. Their receipt showed they were charged an extra 40 cents for each sauce - a total of $1.20.
At this stage Mrs Price became anxious and began vomiting her meal.
Burger King general marketing manager James Woodbridge said the normal process was for a customer to download the app and spend $5 on the app. The customer was then sent 490 "crowns" which they could then redeem for one of the free promotional meals.
There was no issue if those steps were followed correctly.
"I presume what has happened is the customer has bought an item for $5 and then tried to buy the Whopper meal rather than use their crowns. This is why their account was charged," he said.
"If you can provide me with the customer details we would be happy to find a solution that works for them."
Horowhenua Chronicle put the promotion to the test when ordering $5 worth of food and downloading the app.
After the order was placed a promo code was given, that in turn was exchanged into crowns and a receipt for a free meal.
In hindsight, Bennett said despite now reading the fine print numerous times and understanding the process, she still believed it was misleading.
When Rodney and Maryanne had added the extra meals the order form showed a balance of $0.00, which suggested the promotion was honoured.
Bennett said she thought the app needed changing to show more clarity for first-time users.
"I bet we aren't the only people to do that when using it for the first time," she said.
Mr and Mrs Price married on Guy Fawkes Day in 1995 and were due to soon celebrate their 25th wedding anniversary.
Mr Price worked as a volunteer for local organisation Riding for the Disabled.