My reply to them:-
Thank you for your letter.
I am rather puzzled by "We do everything in our control to ensure that we do not send any unwanted e mails i.e. we always ensure that we follow strict processes and will only purchase data from reputable sources who guarantee that addresses are not unsolicited as your letter suggests."
You cannot "purchase" my email address in any way that allows you to send such emails.
For you to comply with the law *you* would need consent from *me*. No consent I give to a third party meets that. Any consent I give to some third party (which I have not) is not something you can buy. I am concerned that you do not understand this point. None of the addresses you buy that may be individual subscribers can legally be sent unsolicited marketing emails.
Any email address you have purchased that is an individual subscriber and to which you send unsolicited marketing emails means you are criminally breaking the law. It is as simple as that. It makes you a criminal. And it means the victim can claim compensation as well as requiring the ICO to exercise enforcement action and pursue criminal charges and penalties.
If you are agreeing to comply with the law, and pay me the amount you offer of £50, I am prepared to agree that I will not pursue a claim against you in the county court for compensation for your emails to me at firstname.lastname@example.org, advertising a fuel card/discount for WM Morrisons fuel purchases.
Payment will need to be made to myself by bank transfer, sort code 20-16-99, 20556858, ref PENC-MORRISON.