Selling my number without consent

I was contacted with offers for cellphone upgrades by Mondo Mobile, upon asking them where they got my number from, they told me that they purchased it from Telegenix Trading. Now I would like to know what gives Telegenix the right to sell my number, as I am not a client of theirs and I am registered with the National Opt Out service and have been for over a year now. Further more I want to know where they got my number in the first place.<br>