Mod on WooCommerce Bookign Plugin

Hello, We are looking to modify an already existing plugin that we have purchased. [login to view URL] This plugin has the ability to add multiple time slots. What we need is to modify to give control over what times show according to the time of year the booking is placed on. We need this in the case of tours that have varying start times according to season. eg Jan 1 - Mar 1 Times available: 4:30 PM, 5:30 PM Mar 2 - July 1 Times available: 6:30 PM, 7:30 PM July 2 - Sep 1 Times available: 8:30 PM, 5930 PM etc So this means if a user selects Feb 5, the times 4:30 PM, 5:30 PM are selectable. If they pick April 7, the times 6:30 PM, 7:30 PM are selectable. You will complete work on our test server.