My DCs recently planned to do a sponsored walk and got a lot of money from family and friends in sponsorship (about £100).
On the day of the walk it all went wrong as someone was threatened with a sexual assault and some wimpy father called the police. This put an end to the walk 
I am so annoyed with this over-reaction that I utterly refuse to send the [unearned] money to the charity it was intended for.
I can't imagine finding the time to send the money back to its donors. Of course I would never spend it. AIBU to just sort of leave it?