I have had half a dozen missed calls from this number and they haven't left a message. If it was legit surely they would ask me to call them back?

Caller was from Priceline (the cosmetics/pharmacy chain) trying to sell me some sort of accident insurance product, since I am signed up to their loyalty card. I think I'll see if I can cancel the card...

Caller does not leave a message and when I call back they hang up!