Brilliant, so I have sent the form two times in the last 10 days and have received two emails, one says my message has been received, the other tells me that

"This is the mail system at host nxvlgmailconfirm02-mailsales.mail.vueling.com.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below."

So I don't even know if they received it or not.

What are the official government agencies where to pursue the compensation?