@Eric144, as an experienced host, I would not advise blocking the calendar on behalf os a guest who is not booked for the dates, and particularly someone who has expressed reluctance over payments. Just stick with the regular methods of transactions, especially if you are new to hosting.
Check the Help Centre for hosting guidance, just type in topic words and then read up on subjects related to hosting and particular areas of interest. This will mean you are better prepared for the range of enquiries that will come your way in the future. Will reduce stress and confusion for you and any potential guests as well.
If the normal procedures don't suit this guest, then pass on the request or just send a reqular acceptance , if they decide they dont want to pay the amount or in one block they can let the offer expire. You will have acted correctly and kept your response rates healthy as well. Good luck and well done in asking for advice on this matter. Regards, Christine