Marketing call and rude consultant

I received a cold marketing call the other day and when I politely said I wasn't interested the lady said nothing and hung up the phone.<br> Firstly, I would like to know where you got my telephone number from?<br> Secondly, I am on the DMA National Opt Out database so would like to know why I am getting calls at all?<br> Thirdly, is it common practise for your \sales"people to behave so rudely towards their potential customers?"""