The evidence is in my inbox. A high street shop asked for my e-mail, I decided to give them the benefit of the doubt (because of GDPR and all that). Of course I then received an e-mail from a third-party asking me about "feedback" (and no doubt it would've been shared with other third-parties behind the scenes too). I'm pretty sure I made a GDPR complaint but it didn't go anywhere.

The GDPR is a joke and will never be taken seriously until those promised "4% of global turnover" fines actually start falling down on the offenders.