It's a bit off-topic but actually similar in many respects. I've become sick to death of call centre operators who ring at evening meal time and try to run a spiel past you that you've been "specially selected" blah blah. They'll never give an address from which they're calling or a number you can phone them back on. They'll never send any hard copy to peruse because it's always a "special deal, only available over the phone tonight". Most of them have Indian accents.
I'm retired now, but when I was doing international consulting for a major US corporation they charged the clients $2500 per day for my time.
I have now taken to pointing this out to the unwanted callers, telling them that this equates to $5 per minute, and how much of my time are they wanting to buy in order to tell me about their offer. That usually results in an immediate hang-up but for those that persist I simply tell them that when they have deposited 20 minutes worth of time to my bank account they can ring back, I'll go online to check that the payment has been received and then I'll take their call. At the end of 20 minutes I'll hang up whether they're finished or not.
You can hear the confusion and choking all the way to Bangalore.