What does the man want?

M：I picked up a cell phone here some days ago，but there is something wrong with the screen. It keeps blinking out all the time. I would like an exchange on it，please.
W：Of course，sir. Why don’t you give that to me，and I can get you a new one from the back room right now?
M：Actually，I was wondering if I could take another model instead? I was told that the new X-300 model has far more functions than the one I got. Do you have it in stock now?
W：Yes，we do，and I think you have made a wise choice. This particular model was only released three days ago，and they’re selling like hot cakes. Of course, it is a bit more expensive，and you will have to pay for the difference， but I think it will be well worth your money.
Number 53.What does the man want?
Number 54.What is mentioned about the X-300 model?
Number 55.Who is the man talking with?