Appointments was working for a month and now problem

Hello there,

I don't know what happened or when the problem first occurred but I just went to my appointments page and it showed this message.

"Fatal error: Call to undefined method Appointments::appointments_get_worker_working_hours() in ***wp-content/plugins/appointments/includes/pro/includes/addons/app-schedule-tetris.php on line 78"

I deactivated the tetris add-on and the calendar showed up but in a messed up way without the dates. So I'm not sure what's going on and I need to use the Tetris mode if at all possible. I granted support access. Thank you in advance.