I wouldn't have waited either. They were told that the spot would not be held unless they gave you a start date and paid the deposit and they did neither so I wouldn't feel bad about it. BC's letter is a perfect example of what my response would be. The only thing that I would do different is not relying on email as the only form of communication. I would first call and speak to them by telephone and follow it up by an email. Not everyone checks their email regularly and some barely check it at all.
Once I figured I'd continue my search for another child I would have called again and sent another email explaining that I would continue to look for someone to fill the spot but neither are necessary. The family was aware of the requirements and they didn't meet them. Of course if you have another fam giving you problems or that is paying less this could be your chance to offer them a bump up to more hours or give them notice. If you don't want to do that and simply can't take this other family then just copy and paste BC's letter and send them an email
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