@Serena216 Your calendar, if not mistaken, is still allowing guests to book only 3 days during next 'summer', I tried duringJune, 2019. A few times this has happened to me (my mistake), and I simply filled the other 4 days with someone else and left it at that.
What would really bother me, is the guest totally ignoring my messages. And no I wouldn't worry about $50 if I didn't want them to come.
I gather preserving the chance of being a Superhost is not a consideration, a chance killed for a full year by cancelling someone.