casewindow: One thing you can do to limit calls of any type is to put your details on the do-not-call list (there is also a do-not-mail list).
If you do get calls (though they need to be from a person) then say that you're on the list.
Just be aware this Do Not Call list only applies to members of the Marketing Assocation. Is is not a telco industry led database, and as a result doesn't prevent telmarketing calls.
As for the original call it's highly unlikely it falls foul of any laws. Tell you don't want to be called again by then, if you are then you can take things further.
Telemarketers are a reality of life now.