Beware "€10 cashback!" Ticketmaster,IrishRail,Ryan,eBay

So, I followed the email on this website here - https://www.completesavings.ie/Features/Common/ContactUs.rails - and emailed it. Here’s the answer I received: Delivery has failed to these recipients or groups:
customerservice@completesavings.ie (MAILTO:customerservice@completesavings.ie)
Your message couldn't be delivered. Despite repeated attempts to deliver your message, querying the Domain Name System (DNS) for the recipient's domain location information failed.”

So, what is the next step? I want them to refund me, remove all my details and never take money from my account again. Their phone line is not being answered, and a ‘delivery failure’ email return when the email on their website is used. Is this a case of they’ve just taken my money and ran without any follow up?

These guys are still at it over 10 years on. A friend of mine got caught after conducting car hire booking with an established company. It is very sneaky the way they tag their "hook" on to the end of a legitimate site.

As I mentioned nearly 10 years ago the practice is an example of Post-transaction marketing.

Such marketing practices "exploit consumers' expectations about the online 'checkout' process." Their "Misleading 'Yes' and 'Continue' buttons cause consumers to reasonably think they are completing the original transaction, rather than entering into a new, ongoing financial relationship with a membership club.

Is there any way ordinary decent companies can be encouraged to discontinue such practices?