Offering lower rate credit card

He is offering me to lower my credit card interest on all my card. He keep saying that he can see all my b illing statements from last month and he have not ask for my name yet. Then when I asked for his name coz I what to know if that call is legit he said James Howard. And I asked him why is it that he is using a cellphone number not a landline number. And he cant answer right away.