Yes I also did face the same problem. They did have a problem ERROR 500 for a few days.
I contact them and it was all OK after that.
According to them it is because they were upgrading the website from shop to rightbraineducationlibrary.com
They did apologize for that.
I have been using the website for already more than 2 years and so far I am very happy with their services.
I guess 3 days won't die.
When I started with the shop they only have 10,000 flashcards now got 15,000 Shichida flashcard.
So cannot complain.
At least dont't have to go everywhere looking for flashcards. I really save my time.