"Last year he saved up to get his first remote car, this year he wanted a bigger remote car.
"It's his treasure box, he wanted the gold coins, collected from selling feijoas, to be his treasure."
Last week, Stefanie was out gardening when she saw a car pull up next to the honesty box.
"I thought they were grabbing feijoas. I went to refill the box and saw it had gone.
"I assume people just took it for the money. There wasn't much there, just about $15."
She says the box means a whole lot more than the money.
"After the theft Sebastian was trying to be brave. He thought he shouldn't have used it as an honesty box, but he is 'big boy sad'.
Stefanie said they had told Sebastian's Oma about the theft and she had tried to comfort him.
"She's trying to find him the same box. His birthday is in July - she's hoping she can get a new one for him, but she is unlikely to get the same one."
Her views on the suburb they live in have changed after the theft.
"We had heard a few stories about honesty boxes - if you don't nail them to the fence they disappear. But we didn't think about it.
"We moved here, to Napier South, because it is a nice, quiet street.
"Now I think it doesn't really matter which suburb you live in, there are scumbags all over."
She said the honesty box was a way of teaching her son the value of hard work.
"He collected the feijoas, cleaned them and packed them up to sell them."
Sebastian has not been deterred by the theft and is starting all over again with his feijoa fundraiser.
"We have put a cheeky sign next to it saying 'please do not take honesty box'," Stefanie said.
The "treasure box" is yellowish gold with a money slot and old-school Disney characters including Mickey Mouse and Pluto.
"We would love to get it back."
