I read about this scam in the Daily Mail recently.
It seems to revolve around school books.
They are probably recording the conversation and hoping that you will not deny ordering it and can then use the recording to chase for money.
They may also be hoping you'll agree to sign up for it - but seems unlikely.
I would ignore it - I don't think you'll see a parcel. Some poor souls actually agreed to sign up for the sponsoring of such schemes and then got chased for the money.