“We’ll unsubscribe you from our mailing list within ten business days” should be illegal. There’s zero reason to not do it right now, except that you want to keep spamming me.
Chancellors estate agents kept spamming me because their contacts database said I owned the house I was renting. So I said I would charge them £50 a go in future for freelance database updating services, any further correspondence taken as acceptance of contract. They stopped.
They need to package up your request with the others and send the bundle with an employee who follows a path visible only during a specific moon phase to the email factory to emphatically petition the removal on your behalf. It's quite complicated, really.
Also on: @benwerd