Not receving email

Not receving email

We've just signed our entire company over to Zoho mail (free for now as a trial, but we were considering uprgrading to a paid account) but after only 2 days of using the service, sadly we are very disappointed. Some emails we write are not being delivered at all. We are sometimes receiving emails, but hours after they've been sent to us. Other emails, we are not receiving at all. 

Looking through the forum, it seems this is a common occurrence. Is this going to be resolved or are we better off finding another provider? We cannot be efficient in our business if we are not receiving important emails, and ours are not being received. 

Thanks for any advice you can give me