No Summer Fun at the Stables

On a typical summer schedule, the girls would have lots of activities to keep them busy. When they fill in a few days hanging out with friends, they have a full, fun summer. This year we didn't make a lot of plans. We thought they were going to spend their summer working at the stable.
It all started with an email asking for summer camp workers. The girls wouldn't get paid since they are not old enough to work. They would receive credit they could use for lessons or share boarding. When we went to the meeting, the leader said she needed as many people as possible for as many hours are possible. She painted a picture in which everyone was having fun all summer while earning money/credits.
The girls were so excited. They created a plan in which they would earn enough money to share board a horse. They figured out how many hours they had to work to pay for one year. They started planning to purchase halters and bridles and other stuff.
The first week came and went. The second week came and went. We heard nothing from the stable about the girls' work hours. I emailed several times asking about a schedule. I asked the leader when I saw her at a horseback riding lesson. We never heard anything. To date we have never once received any communication about not being on the schedule.
At this point it's clear that the girls are not going to work this summer. She oversold the entire program, giving the girls false hope.
We wanted to teach the girls a lesson about being responsible and earning their own funds. They were supposed to spend the summer working hard and learning important lessons that would give them a solid foundation for other projects.
Instead we're scrambling to figure out how to fill their days. We decided to stop waiting for work assignments after the brunette twin started crying. She said she realized that they were not going to work enough to share board a horse. She said her dream was crushed.
What makes me really angry is that the girls are not just summer workers. They take horseback riding lessons. We pay a hefty monthly price for those lessons. The girls are summer workers and customers. If the leader didn't want to be professional towards her summer employees, you'd think that she would think about being professional towards her customers.