In the entire vocabulary of human existence, there is one word that can be used in a situation like this - "no". Just say "no" to everything they propose to you and at the end of all this, use just one other word (clause?) - "OK?"
me usually ignore unregistered and unfamiliar numbers these days, once in a while would then decide to hear what these chaps have to offer. besides the usual CC promotion, heard one asking if me had any bad debt to collect and they'd help me do so for a fee.
anyway, encountered this incidence once and it's rather amusing. the guy on the other end of the line was recognisably a Pinoy, spoke in a cheerful manner, asking me if me wanted to take up some loan.
p(Pinoy): Good Afternoon, Sir, is this XXX that I'm speaking to?
m(me): err... yes, speaking.
p: hi Sir, I'm calling from *** bank and I would like to extend this ***** (product) to you, Sir
m: err... i'm not interested, thank you
p: but this (product) offers ******** (whole load of jibberish which me can't recall now)
m: but i'm not interested, thank you
p: could you let me know why you aren't interested? I'm doing a survey to collate the responses to find out what's wrong with the product.
m: i'm just not interested in purchasing any product.
p: is it because the rates aren't attractive enough? I have another product ****** (went on in jibberish mode again)
m: i'm not interested in that either.
p: could you let me know if there's anything wrong with the product which made you lose interest in this product?
m: just not interested.
p: could you let me know the reason why because I'm collecting the responses from the customers on why they dislike this product, Sir
m: just not interested in it, that's all.
p: oh... ok, Sir, thank you for your time, Sir *click*
guess they do take "no" for an answer for this one, but the following incident was hilarious. was driving with the phone clipped onto the phone holder, this guy (another Pinoy) made my day.
p: hi Sir, am I speaking with XXX? I'm calling from ***** bank...
m: yes, speaking
p: (one full load of jibberish on the product in a very short amount of time) *click*
m: no
the telemarketeer had clairvoyance!