I used Voki Presenter for about 4 years for short introductions to each weeks work. This year half of my presentations are missing. Even after many emails and help requests no one answers my question, where are my missing presentations and what do/pay?

I've use Voki for 3 years for short introductions to my college class. This year 6 presentations are missing. After several emails no one answers my help requests. What do I have to do or pay to get my earlier presentation back? My class starts in 2 weeks. Jim