Not saving

I am trying to build a website using the 'FIXER' theme, and I keep losing all of my work. Every time I hit 'save' I get a message that says 'There was an error saving your changes'. I have wasted a few hours now trying to build a site that won't save. I am on a free trial and would like it renewed once this problem is resolved please. So far I have done nothing but waste valuable time on this. How can I resolve this?

Thanks.