Pressing one on any unsolicited telephone call could take you through to a premium rate line and the cost could be very very high; especially if you were to do as suggested by Martin ^^^.
If a real person speaks to you the moment your answer the call, then by all means 'string them along' for as long as possible. Then tell them as, I do when they ask for payment by card, "I am unable to pass money by card, but if you give me your bank details I can arrange a transfer of money from my bank."
Hans.