Tested few times (even with TOR browser) I can confirm the registration is ok now. The same problem with the registration appeared after the confirmation link, now is fixed as well. First registration just took place.
About the payments. I'm using bitcoin full node at the moment for the payments, if I have problems I'll consider using outside service like yours. Thanks for the suggestion. It's good to have options.
Sorry, still not working.

I try to login but get error. Clicked on "Lost Password", wrote my email, but it says "Wrong information is provided."
There is something wrong there, because it's the same email I received my confirmation link and now it's not being accepted.