Common to the cases is, that they all involve e-mail accounts from major providers, like GMail, Hotmail and Yahoo mail. We have found that the attacks on GMail accounts involve changes to the account filters. That means that the attacker creates filters that cause enquiry e-mails to skip the inbox so you don't see them. These filters can be for words like "inquiry", "enquiry", "vacation" "ID" which means that if an email with these words is sent to your GMail, it will be forwarded to the hackers instead.
The the hacker receives them and answers them on your behalf. We therefore strongly recommend that you log in to your GMail account, click on the gear icon, select "Settings".Find the "Filters" tab and make sure that there are no filters.
Here is an example of how it would look like if someone added filters to your account:
If you see something like shown above, please save a screenshot and contact our support immediately. We can help you to remove them or you can also remove them directly and change your password.
For questions or doubts, contact support@spain-holiday.com or +34 952 204 435 or +44 2033 847066.