That is absolutely horrible! Shame on them. You have every right to complain.
If I were you, I would call them on Monday (I think they have a toll free number) to get the situation resolved ASAP. I have heard too many stories about e-mails getting lost or ending up in spam filters to trust it, not with HCG specifically but with mail order nurseries in general.
Let us know how it works out. I have a somewhat large order from HCG coming at the end of April. I hope I will not be disappointed!