in the .htaccess file of your document root, this request limit should be disabled. If your host does not allow overrides this way, you can ask your provider to include the directive manually in the Virtual host configuration of your site. That could be the moment you discover that the hosting provider is not offering you the service you need.
This is the one and only official site for Appointment Booking Pro. If you downloaded ABPro from somewhere other than AppointmentBookingPro.com, you may have a copy lacking the latest security features, and/or a copy with malware attached to it. It's your business - or your client's business, only run it on real ABPro.