Buyers ordering without messaging first and expecting hours of work for $5!!

I'm sure this was mentioned before but was not able to find it in the most recent discussions. Recently I've been having a lot of people order from me without messaging me first. On each gig, I have it very clear that people must contact me first before ordering. I assist clients for my virtual assistant work outside of fiverr and may not always be available here depending on the tasks. I made my gigs for 7-10 days in case an order takes more time. Also most of the orders are for tasks that are in depth and will take more than 45 minutes (what I offer for $5). When I tell them this, they get mad.

So, besides asking to mutually cancel the order (which I have been doing), is there anything else that I can do?
I read that mutual cancellations don't count but I feel that they do. It also raises my percentage of cancellations.

I know there are most likely many sellers dealing with my situation and would appreciate any advice.

Thanks so much!