I had the same experience in terms of receiving a PayPal payment confirmation, but not a separate MovieMars acknowledgment. When I emailed them about the status of the order, I just referred to the order number in the PayPal confirmation, and they responded within a business day or two. I think their customer service is US-based and only available on business days, so you'll probably hear back tomorrow or Wednesday, I'd imagine. Over the years, I've found with them--similar to other online retailers like ImportCDs, DeepDiscount, Caiman (a blast from the past), etc.--that it may occasionally take reaching out more than once, and there may be an occasional screw-up in terms of whether something you order is actually in stock, but they eventually make it right one way or another.
See my post above in response to mjzee.