Here in Spain we also receive many calls from telecom companies asking to "talk with the line holder", of course offering prices "you can't refuse".
As they're charged for the minutes they have the line occupied with you, instead of hanging up the phone, I try to catch their attention as long as possible. So, I tell them I'm not the line holder, but that I can pass them with that person if they want to. Obviously they always say "yes" and then I simply put the hands-free on, and (my iTunes is usually open as I like working listening to music) I put them the song "Mah Na Mah Na" from the Muppets Show soundtrack...
I continue working with a smile, waiting for them to hang up from their side, after listening - sometimes many minutes - to " Mahna Mahna - Do doo be-do-do - Mahna Mahna - Do do-do do - Mahna Mahna - Do doo be-do-do be-do-do be-do-do be-do-do-doodle do do do-doo do!"
https://www.youtube.com/watch?v=8N_tupPBtWQ 
