E-chuggered by Mencap

Early morning email from Mencap, with exciting news and fundraising pleas. Apparently, I received this because I'd given consent to being contacted by them. Except I haven't. Also, although the e-mail, right at the end, states I can 'unsubscribe', there was no link allowing me to do so.
Now, I know that Mencap does vitally important work, but this kind of unsolicited e-begging (as with postal pestering and on street chuggering) seriously reduces the good name of many charities. Yes, I know times are hard financially, and that their are a lot of causes competing for money. But it starts to feel rather underhand when appeals masquerade as news, surveys or questionnaires, or when charities buy in the names and addresses of the provenly pesterable, based presumably on prior giving to comparable causes.