Plugin Not Updating with Latest Search

Hello,

Since the latest update of the plugin and/or updating to the latest version of WordPress (4.8.1) on my site the prices and chosen dates aren’t updating each time I change to new date in the search box. So the price might be correct on the first try but then on my second search, it is remembering a previous search.

The page is https://scotts-farm-camping.co.uk/price-checker/

I’ve tried many things including activating and deactivating the plugin, reinstalling it, clicking update on each price or on the rooms and checking for plugin conflicts. Are you able to shed any light on it?

Thanks

The page I need help with: [log in to see the link]