if CAA didn't disclose (or disclose enough info) about their connection/data-sharing with trip case, then your beef should be with CAA

If CAA did disclose it under their verbose TOS, then it's your fault for not reading it (and also every company's fault for having a long verbose TOS that no one reads)

If tripcase continues to spam you after you unsubscribe, then talk to their regulator (they're owned by sabre , located in usa, so the Canspam act should apply... Not all emails from them would qualify as spam though, eg if airline uses them to send actual useful transactional stuff like flight confirmation emails)

Regardless, it's a free market. Now that you know CAA gives info to tripcase:

1) stop using CAA (too bad if there are no alternative flights)
2) complain to CAA. Enough people complain, they'll stop using tripcase

Good luck with (2)... Sabre owns a lot of other companies too