How did you file your first home GST/HST rebate?

When tring to file a GST/HST rebate online on the CRA site for first home GST rebate, I can never submit the form successfully...

Whenever I reach the end of the form, it says:

This service is not available at this time. Please try again later.

If you have filed the rebate, how did you submit it? if it is by paper, where did you mail the form to?

Annnnnd more importantly, has anyone gotten the rebate!?