Error - customer not receiving translated emails at sign-up

Hi,

I have sent an email to support about this more than 48 hours ago, but haven't received any response yet and this morning, after many months' work, is supposed to be our launch day. As we are launching to 100% Spanish speakers on our email list, we cannot until this critical bug/error is fixed.

If anyone can help, I'd be very grateful as we're getting pretty desperate now after two days of waiting! Here's the problem:

We have a sign-up form in Spanish. I have added the _lang=es to force the page into Spanish as the customer is a Spanish speaker coming from our Spanish website. I am also based in Spain right now, and using Firefox with ONLY Spanish set as a content language.

I then sign-up on that page.

After sign up and payment, I receive three emails:

1. Sign up Messages > Send Registration E-Mail (RECEIVED IN SPANISH)
2. Messages to customer after payment > E-Mail Payment Receipt to user (RECEIVED IN ENGLISH)
3. Messages to customer after payment > Send Signup E-Mail (RECEIVED IN ENGLISH)

Now all the above emails are translated into Spanish under Config/Set-up > Email, and up to a few days ago, they were all received in Spanish by someone signing-up with the language selector on the sign-up form set to "Español".

However, I have tried this with 4-5 new users, all submitting the sign-up form with the page language set to Spanish. All the users receive 1 email in Spanish and 2 emails in English. If I log out and log in with those same users, their account pages are all in Spanish, so it has obviously registered that Spanish is their profile language but for some reason it is ignoring these two translated emails:

E-Mail Payment Receipt to user
Send Signup E-Mail

I have been in and recreated/re-saved the above translations several times, but they are still ignored and the user still receives them in English.

Two days ago I sent a detailed email to Support with the admin login information, FTP information etc. Please can someone look for it? Or if anyone using the system has come across this bug, could you please explain how to fix it so I can have a go myself?

I'm really hoping that we can get this fixed this morning as otherwise we're going to have to delay the launch and re-write and re-translate a lot of our launch materials (because we've already mailed thousands of people on our email lists telling them the launch dates for a start).

Thank you,