When you say you "answered" two calls, do you mean you dialled some number you were given back, or just picked up the incoming call and were charged for it? If the latter, then I'm astonished you can be charged for receiving an incoming call, and were it me, it'd certainly generate an enquiry to my service provider and a complaint to OfCom.
As for getting cold calls from details given to confused.com, they've admitted it happened, but is was, they say, a breach of their contracts.
See
The Times
This, however, is why I don't give out my phone number lightly. I
never give out my home phone number like this, and only very, very rarely will supply even a mobile number, and only
ever to companies I know and trust. If a web form won't complete without a phone number, it'll either get a made up one (like 01234 123456) or I'll simply find another company and ditch that form altogether.