Have you had trouble getting message responses from teachers / Italki?

I've sent messages to two teachers, and then sent further reminders to them. I've also written to Italki Support, asking if there are technical issues, or whether there is any way I can see if a message has been sent or received. So far, I've not had a single response to any of these 5 messages.

Before I give up entirely on Italki and look elsewhere for an online teacher, I want to ask -- have other people had similar problems getting answers to messages?

My messages to the teachers were detailed, serious inquiries, explaining that I wanted to invest in a number of lessons over the Christmas / New Year period. Anyone had a similar experience, or have I just been unlucky?