To think that Boots shouldn't send letters to customers who have opted out of marketing communication

[AwakeCantSleep]

asking them to opt in again?

I'm genuinely puzzled why they would think this was a good idea. The letter says ".. since you don't get our regular mailings, we just wanted to remind you that you could be receiving personalised offers" etc. And then "We hope you choose to hear more from us".

Yes I COULD receive such offers but I don't want to, hence I have opted out.

Send it back with other junk mail you've had from different companies... "Since I opted out of your mailing list, have this back and some of my other junk mail too...to redress the balance"